I experience this too. I can turn loops 9 and 10 ON in the software editor. I can turn them OFF on the PBC, but not ON.
What do you mean by "turn ON" or "turn OFF"?? You mean the loop itself, or the parallel part? If you post your file I can probably help...
I can turn off parallel no problem on PBC.
In this scenario, I can have loops 7-10 parallel enabled. In theory I should be able to turn trails on and off. I can do this with loops 7 and 8. 9 and 10 won't allow me to turn trails on (this is all on the unit itself). If I turn trails on in the software editor then sync, trails will be on. Then if I go back to the PBC, I can turn off trails on loops 9 and 10, but cannot re-enable them.
To me, this seems like a bug on the unit itself.