The export will only work for one of the active GTO+ windows (the first one that was opened).

I have just checked, and over here I can export from v156 to v211.

A requirement for exporting from GTO+ to FlopzillaPro is:
1) Both programs use the same port number under “Configuration->FlopzillaPro” and “Configuration->GTO+”
2) FlopzillaPro needs to be open on your computer
3) FlopzillaPro needs to run on the same computer as GTO+. If FlopzillaPro is detected in GTO+, a green circle will be displayed in the lower left of its interface. See the screenshot below.

Should your issue persist, then try setting a different port number for both programs under item 1).
You will need to restart both programs for the change to take effect.

Scylla

The drill line that has been selected is Check-Bet-Call -> Check-Check, whereas the displayed line is Check-Bet-Call ->Check-Bet-...
So, judging from the screenshot, it appears that the wrong line has been selected.

I have tried with a different tree over here, and did not experience a crash.
So the issue may be dependent on some tree-specific properties.
Is it possible for you to send a savefile to support?
If the issue is reproducible, then we'll take care of a fix.