VarAC freezes trying Broadcast

I'm an old hat at FT8. Using this new software has exciting potential and i look forward to using it more. My current setup (below) is straightforward and has always worked well with digital in the past:

VarAC 6.2.4

VARA HF 4.6.7

IC-7300

EFHW / 20W

Win 11 / LG-Gram

My new first try on air with this - successfully sent message to another station and also received unsolicited message back from a second station... So, all seems well, so far.

Before calling it a success and shutting it down, I decided to do a broadcast which 'started'... but abruptly failed/paused. Did it transmit entire message (?) - i'm not sure. The transmitter keyed and started a TX, but audio stopped after couple seconds. Rig stayed keyed for ~20 seconds with no further audio transmition, then (built-in watchdog timer) shut it down, for safety reasons. VaAC was 'stuck' with displaying busy (frequency was clear) and unusable, until shut down and restarted...

Ideas?