What is the problem?
When applying loop effects on the Play in Performance mode, for now it doesn’t matter what tracks you choose - it just loops them all.
According to the Polyend Play manual:
In the case of most of the punch-in effects, only the selected tracks will be affected. If no track is selected then changes will not be audible. The exceptions are the eight Reverb preset, and all the Loop effects.
What do you want to achieve?
An option to make loop effects work just with selected tracks as other effects do.
Preferably, not global, but adjustable per grid button (if/when it’s possible: Performance mode: customizable effect values).
Are there any workarounds?
No.