3.4.0 forward: Interfaces recording on one channel only

We have hundreds of clients we train using Audacity. Most were Windows users, fewer use Macs. When those using interfaces migrated from 3.3.3 to 3.4.0(+), we began to notice modulation problems in Mono recordings. We began surveying those and found that their interfaces (Focusrite primarily) were recording on 1 channel clearly with the second channel recording at a minimal Gain. When rendered to Mono, the recordings produced high amounts of modulation - as if Audacity were adding Gain to the second channel in order to make up for the low Gain recorded. It continues to happen. We have tried to work around it using Control 2 software from Focusrite by Linking the two Analogue channels. Sometimes it works. Other times it does not work. As the issue didn’t begin happening until the move from 3.3.3, we feel confident that something has been missed in the new releases that allows for this miscommunication between Audacity software and interfaces. Can you assist with solutions, workarounds, or patches that will mitigate our findings?