As nobody else has reported this I'm assuming it's just me.
The vol, pan and wid knob stacks of both the tcp and mcp display their old knob images beneath/behind them, or if they're not present the gen_knob_bg ones.
If you use a circular image, chances are the old ones will be covered and you'll never notice, but if you don't...
Steve
Sadly the attachment manager keep changing the png example I want to attach into a jpg!
https://stash.reaper.fm/13277/tcp_wid_knob_stack.png
Got one, if you use this you should be able to see part of anything beneath.