icloud account no longer syncing or syncing very very very slowly

All of a sudden, Wednesday morning my emails no longer sync or sync very very very slowly with my email account which is icloud. 
My icloud account is synced with my ipad, iphone and PC.  All works as perfectly as it always has on my ipad and iphone but no longer on my PC (eMclient).
I haven’t touched any parameters anywhere.

The worst is the sent items. 
I can write and send an email in eMclient.  It is sent and delivered and it appears in eMclient Sent items but it never appears in my other devices sent items.
Same problem the other way around.  If I send an item from my phone, it sends and it appears in my phone sent items but not in my pc emclient sent items.

Eveything was working perfectly since 6 weeks that I installed eMclient but since 2 days ago, the above problems can’t seem to stop.

I’m having the same problem. Use iCloud exclusively and have never had any problems before. Last couple of days it is constantly pausing while syncing the sent folder or outbox. Repairing the folder seems to help initially, but then it just starts hanging again.