Can't get courses offline

Dear Memrise Team
I have upgraded to the pro version because I wanted to download courses offline, however I was only able to download small sized courses that contains up too 200 items. When I try to download bigger courses. I get an error. I have tried tens of times downloading over many networks but this didn’t work.

App is up to date: 2.9_3892.
Courses I failed to download:
/course/948/sat-comprehensive/
/course/11682/advanced-english-c1-c2/

I hope you find a solution for this problem. I have read on the knowledge base somewhere that the app has issues with bigger courses, so I suggest you find a method to download an offline file and place it somewhere on the device and the reason is that good courses are not very common, and mostly they are big in size, so if I can’t download at least one good course, why the offline mode is created anyway ?!
Thank you

Problem:

Downloading:

Update:
I would like to say that the problem is resolved and yesterday, I was able to download all the courses, so if somebody worked on this, I would like to say Thank you so much.