weird position bug when enabling record

[catfact]

see this thread:
https://llllllll.co/t/norns-2-0-softcut/20550/147?u=zebra

under some condition, which is not yet understood, enabling record flag on a playing voice will cause material to be written to the wrong part of the buffer.

it seems likely that the inactive sub-head is erroneously writing (?)

i will work on a minimal repro case. but the example case goes like this:

1. enable rec, start playing
2. set loop endpoint, jump to loop beginning, disable rec
3. enable rec in the middle of the loop, before reaching the loop endpoint. new audio is erroneously written to the beginning of the loop.

if step (3) occurs after a loop has already happened, the problem isn't seen.