Cannot start MOC - "No valid sound driver found" in Ubuntu 20.04

I had to hard-reboot my Raspberry Pi (unplug the power) running Ubuntu Server 20.04 and since then I cannot run the console music playermocp anymore. The program runs through the initialization of OSS and ALSA drivers, then fails with the message FATAL_ERROR: No valid sound driver! I have tried purging the package (via apt-get purge mocp) and reinstalling it, but the error message remains. Googling around this question brings up a few very old threads ([here](https://moc.daper.net/node/485) and [here](http://moc.daper.net/node/278)) on MOC's own discussion boards, suggesting this to be either an ALSA issue or with the sound card, but I'm not sure about this since when I run alsamixer it starts and I can do things like change the volume of it. Plus, if run other programs that use audio like mpg123 the audio is fine. Detailed error log extracted with mocp -F is shown below, sorry if it's a little verbose. Does anybody know what might be causing this? Many thanks! Aug 31 15:34:23.139072: main.c:1191 main(): This is Music On Console (version 2.6-alpha3) Aug 31 15:34:23.139216: main.c:1195 main(): Configured: '--build=arm-linux-gnueabihf' '--prefix=/usr' '--includedir=${prefix}/include' '--mandir=${prefix}/share/man' '--infodir=${prefix}/share/info' '--sysconfdir=/etc' '--localstatedir=/var' '--disable-silent-rules' '--libdir=${prefix}/lib/arm-linux-gnueabihf' '--runstatedir=/run' '--disable-maintainer-mode' '--disable-dependency-tracking' 'build_alias=arm-linux-gnueabihf' 'CFLAGS=-g -O2 -fdebug-prefix-map=/build/moc-NiZ4Xl/moc-2.6.0~svn-r2994=. -fstack-protector-strong -Wformat -Werror=format-security -Wall -pedantic' 'LDFLAGS=-Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,-z,now -Wl,--as-needed' 'CPPFLAGS=-Wdate-time -D_FORTIFY_SOURCE=2' 'CXXFLAGS=-g -O2 -fdebug-prefix-map=/build/moc-NiZ4Xl/moc-2.6.0~svn-r2994=. -fstack-protector-strong -Wformat -Werror=format-security' Aug 31 15:34:23.139240: main.c:1205 main(): Running on: Linux 5.4.0-1015-raspi armv7l Aug 31 15:34:23.140180: main.c:1157 log_command_line(): mocp -F Aug 31 15:34:23.140265: main.c:1171 log_popt_command_line(): mocp --foreground Aug 31 15:34:23.159074: decoder.c:700 load_plugins(): Loaded 11 decoders: aac flac modplug mp3 musepack opus sidplay2 sndfile speex vorbis wavpack Aug 31 15:34:23.159160: server.c:360 server_init(): Starting MOC Server Aug 31 15:34:23.159210: log.c:233 log_init_stream(): Writing log to: stdout Aug 31 15:34:23.159384: server.c:300 log_process_stack_size(): Process's stack size: 8388608 Aug 31 15:34:23.159402: server.c:317 log_pthread_stack_size(): PThread's stack size: 8388608 Trying JACK... Aug 31 15:34:23.160789: jack.c:121 error_cb(): ERROR: JACK: Cannot connect to server socket err = No such file or directory Aug 31 15:34:23.160809: server.c:672 add_event_all(): No events have been added because there are no clients Aug 31 15:34:23.160847: jack.c:121 error_cb(): ERROR: JACK: Cannot connect to server request channel Aug 31 15:34:23.160861: server.c:672 add_event_all(): No events have been added because there are no clients Aug 31 15:34:23.163010: jack.c:121 error_cb(): ERROR: JACK: jack server is not running or cannot be started Aug 31 15:34:23.163028: server.c:672 add_event_all(): No events have been added because there are no clients Aug 31 15:34:23.163298: jack.c:121 error_cb(): ERROR: JACK: JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock Aug 31 15:34:23.163317: server.c:672 add_event_all(): No events have been added because there are no clients Aug 31 15:34:23.163332: jack.c:121 error_cb(): ERROR: JACK: JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock Aug 31 15:34:23.163344: server.c:672 add_event_all(): No events have been added because there are no clients Aug 31 15:34:23.163369: jack.c:148 moc_jack_init(): ERROR: jack_client_open() failed, status = 0x11 Aug 31 15:34:23.163381: server.c:672 add_event_all(): No events have been added because there are no clients Aug 31 15:34:23.163393: jack.c:150 moc_jack_init(): ERROR: Unable to connect to JACK server Aug 31 15:34:23.163404: server.c:672 add_event_all(): No events have been added because there are no clients Trying ALSA... Aug 31 15:34:23.163423: alsa.c:477 alsa_init(): Initialising ALSA device: default Aug 31 15:34:23.165678: alsa.c:365 alsa_init_mixer_channel(): ERROR: Can't find mixer PCM Aug 31 15:34:23.165710: server.c:672 add_event_all(): No events have been added because there are no clients Aug 31 15:34:23.165733: alsa.c:365 alsa_init_mixer_channel(): ERROR: Can't find mixer Master Aug 31 15:34:23.165751: server.c:672 add_event_all(): No events have been added because there are no clients Trying OSS... Aug 31 15:34:23.165829: oss.c:206 oss_init(): ERROR: Can't open mixer device /dev/mixer: No such file or directory Aug 31 15:34:23.165851: server.c:672 add_event_all(): No events have been added because there are no clients Aug 31 15:34:23.165899: oss.c:71 open_dev(): ERROR: Can't open /dev/dsp: No such file or directory Aug 31 15:34:23.165918: server.c:672 add_event_all(): No events have been added because there are no clients Aug 31 15:34:23.165939: oss.c:87 set_capabilities(): ERROR: Can't open the device. Aug 31 15:34:23.165956: server.c:672 add_event_all(): No events have been added because there are no clients Aug 31 15:34:23.166034: audio.c:926 find_working_driver(): FATAL ERROR: No valid sound driver!