Thanks, so your stock firmware 3.12.0-dingux+ 10/27 is the same as mine, and your taking screenshots at GUI are successful. (so no need to change to other stock version, i guess. )
And you mentioned you use another internal sdcard, not the original (toshxxxa ?) one which i am still using.
While testing screenshots in my stock firmware i found another issue, right after taking a screenshot (even with size=0 ) the RG350 restarts itself, 3 out of 5 times ! Would it be insufficient power that not only fails the screenshots but also leads to forced console restart?
Well at least, the other ROGUE firmware has no problems taking screenshots, a workaround. Thanks.