I don’t have a problem highlighting on either size iPad Pro. What version of DTTG2 do you have installed? I had problems with iPad Pro 12.9" freezing during annotation prior to 2.0.8.
Well, you inadvertently solved it. Seriously! Thank you!!
I couldn’t send an exact copy of a PDF because they are confidential records. So I attempted to take one and redact out the confidential information. When I did so it stripped out the OCR. So I used DEVONthink Pro to OCR it, and voilà, problem solved. I tried other documents that I just OCRd in DEVONthink and changed nothing else, and they work perfectly fine within DEVONthink ToGo now, as well. So, that was it.
So, the cause problem is that I had an automated setup that every PDF downloaded to a certain folder was OCRd by ABBYY FineReader Pro for Mac (latest version). Apparently, in spite of the fact that DEVONthink apparently uses the ABBYY engine internally, the mobile version doesn’t like it pure!
Now my solution is to just upload everything to DEVONthink and OCR within DEVONthink and it all works perfectly well!
Thanks for leading me to the solution, I wouldn’t have found it otherwise.