Not sure if this is the appropriate place to report potential bugs, but I will attempt to describe an issue. I recently completed a set of 10 Adventure Lab caches using the new app. I received the confirmation for each one and then the "You've completed the Adventure Lab" message after the 10th find. However, after checking my stats later that night I was only given credit for 9 out of 10. After checking the app again, it also reported only 9 out of 10, even though at the time it showed 10/10 complete. I found out this was also happening to other cachers, so it was not just my app/phone.
I found out afterwards, that the question and answer to the one lab caches was changed at some point (I believe before I actually started the AL). Based on having only done the 1 set of AL caches, it would appear that the question/answer are stored on the app as well as the server. When I answered some of the AL caches wrong, I got an "incorrect" message almost immediately, so it was pretty obvious the answer was not being verified by the server.
I think what is happening is that the server and the app got out of sync when the question was changed. When this happens, the submitted answer is verified by the app, then actually submitted to the server. The server probably reports that the answer is incorrect, but this never makes it back to the app. The app has already marked the answer as correct because it has the old question/answer. So the app eventually gives you the "Completed the Adventure Lab" message because it's not checking with the server and the cacher has no way of knowing they submitted an answer that was not actually accepted by the server.
Eventually the app somehow gets synchronized and receives the new question/answer, and the lab cache is reported as not completed requiring the cacher to return to that GZ and submit the correct answer. It was verified that returning to GZ after this happens does work and allows you to actually complete the Adventure Lab.