I use BlackMagic's Video Assist when shooting chroma key with my EX1R. This gives me ProRes HQ 10-bit files which are quite nice for keying. The VA is automatically triggered whenever I press the EX1R's Record button.
This week, when I used PluralEyes to sync up takes, I noticed that the VA recorded several clips which were valid "takes," where the Sony EX1R did not create a file. The Sony files are sequentially numbered, and there are no missing numbers; the takes jumped from --86 to --87, but there are three VA clips in between. The VA clips are also sequentially numbered, with nothing missing.
I have the VA clips, so there's no crisis here. But I would like to know how this could happen.
Again... once it is set up, I don't even touch the VA; and the VA only records when you press "Record" on the Sony -- but the Sony didn't record all the takes that the VA did.