I, too have had many issues with the BGS app.
In the end, I had to use my Windows 10 laptop, despite many reinstalls, updates etc. just to get the ‘dashboard’ to reflect my progress.
The biggest issue for me, was that most of their course material has not been updated to reflect the 2020 syllabus.
Worse still, their question bank is almost completely useless for the 2020 syllabus exams.
A lot of the content of their question bank is still pertinent, but the way the questions are worded now in the exams, makes them unusable.
Also, there are a lot of questions in the exams which are not even referred to in the BGS notes!
They claim they are working on this, but it really should have been updated by now, or at least split off into the different syllabi, old and new.
I have had to look elsewhere, to find up to date questions and have bought a subscription to ATPLQuestions (?), which appears to be bang up to date, in format and content.
CAPT Online also have some free question banks which are more up to date.
On the plus side, the BGS live and recorded webinars are useful, especially for those tips and mnemonics that you don’t always get from a book.