This issue is minuscule and doesn't have too much of an impact on gameplay.
For this issue, I only used MX-based weapons, excluding the MX SW as that only features automatic fire(you tease me with your lies, MX SW selector switch!), so I cannot say for sure if it will work with other firearms.
While aiming down the TWS scope on semi, switch to full auto. You'll notice thermal is no longer active, despite the user not clicking N. You can still enable thermal on full-auto by hitting N after the issue occurs.
So, like I said, this issue is very minuscule. However, I can see this "bug" being troublesome in situations where quick maneuvers are necessary.