I had a similar thing happen:
RELAY G10, 2 transmitters, fully charged Playing a concert.
Pre-Show (5-10 min) I synced Transmitter1 with Base1 and placed in Guitar1 (JTV69 also connected and powered by VDI/Helix)
Synced Transmitter2 with Base1 and inserted in spare (Guitar2).
First 2 songs have custom tunings from Helix snapshots so VDI is used, but G10 still plugged in output jack for when I disconnect. Volume is obviously up.
4th song I disconnect, no sound, G10 is no longer talking to Base. I would have to plugin to Base and resync to use. Solo passes without me because I'm trying to plug the VDI cable back in to my guitar.
After the song, I noticed the backup guitar also has gone to sleep. I turn up the volume knob and hit the strings a coupla times and it doesn't wake back up either. ?!?!?!
No other bluetooth was in range as far as I know unless it was cellphones in the first couple of rows of the audience, which would've been 30-40 ft away.
Base1 is flashing white the entire time. After a plugin/resyncing, all is well.
I know it enters sleep mode after 4 min of no input, but how long does the unit actually sleep before it needs a resync or turns off altogether? Is there any way to control this behavior? even a hack? If not, these units won't work for me.