Excuse me - I didn't saw it the option, because I was using mobile brouser.
So, I am attaching 3 clips, wich are showing haw the app stop, while trying to mace comment, signature and highlighting.
Thanks for sharing the videos. As we can see from the video, the language on which device is running is Bulgarian. Currently, we are not supporting this language. We will try to fix it soon on Bulgarian. In the meantime, you can switch to English or any supporting locale. You can find the list of the supported locale in the description of adobe acrobat on the play store.
Thanks for your feedback, Could you please share the problematic PDF on adobereader-android@adobe.comand the comment-text? We will look into the issue.