bash: How to prompt for user input while reading file?

Following script statement for user input is nested in while loop under if block but it doesn't work and is being skipped. How do I get user input to work?

3<&0 && read -p 'Enter your answer: ' uservar <&3

FILE="hostnames.txt"
echo $(sudo chmod +777 $FILE)
echo "Step 1. Checking if file with hostnames exists."

#exec 3<&0

if [ -f "$FILE" ]
then
  echo "PASSED: File hostnames.txt does exist." && echo ""
  while IFS= read -r hostname;
    do
     echo "Step 2. Checking Grph mgmt_con_ip4 exists for $hostname"
     mgmt_con_ip4="$(echo "$(llama-grph node show $hostname | grep mgmt_con_i$
     echo "Grph has management IPv4 address: $mgmt_con_ip4"
     if [ -z $mgmt_con_ip4 ]
       then
         echo "PASSED: Grph mgmt_con_ip4 == NULL" && echo ""
       else
         echo "FAILED: Grph mgmt_con_ip4 == NOT NULL" && echo ""
         echo "$(ipam --format json get-cidr-parent $mgmt_con_ip4)" && echo ""
         echo "WARNING: OOB networks shouldn't have $mgmt_con_ip4 IPv4 addres$
         exec 3<&0 && read -p 'Enter your answer: ' uservar <&3
     fi
  done < $FILE
fi