On Mint 21, you have to build 2.5.4 from source, or, use a package from
the Mint 21 repository.
Go here and download the script for Mint 21. Run the script,
instructions inside the script. This will install all of the required
run time and build libraries for WSJT-X, W1HKJ (FLDigi, FLRig, et
I made a copy of the ini file for the condition that connects to Omni-Rig and a
separate ini file copy for the configuration that does not connect to Omni-Rig.
I compared the files using WinMerge. I see no obvious difference that would
explain why one works with Omni-Rig and the other does not
