Nextcloud ios client all fles and folders disappeared

Netcloud for iOS
Nextcloud Server 15.0.2

Yesterday night [Monday 14-01-2019] I noticed something strange with my ios client-

  1. some files where downloading form my nextcloud server [even though i did not initiate any download]
  2. and all the other files and folders disappeared from my files and folders

To check if my client is connected with the server i created two .txt files with the help of the client and they uploaded to my nc server on the pi.

all my old files and folders are on the server as well as the new .txt files

I removed the client from ios device and installed it again.

when i logged in again - only one folder synced [the one that got strangely synced on monday night] and the .txt files i created on monday night.

I am able to create new files and folders in my client and they upload to the server but am not able to download the files and folders that are on the server.
What should I do??