Google sync not working properly after update to 3.4

BUILD ID = OS VERSION (Settings > About product): 3.4
HARDWARE (Jolla1, Tablet, XA2,…): XA2

DESCRIPTION:

Due to several issues after updating to 3.4 I had to reflash my xa2 with the most recent 3.4. After reflashing the phone works well again. However I have a problem with syncing of my google account. After reflashing I tried to restore my backup files. The process was aborted with an error message. I don’t know whether anything was restored. Afterwards I set up my google account. Everything worked at the first moment. It syncs properly, and my contacts are fetched from google. However after some time, the contacts are all gone. I have to go to accounts and press sync again. And so on.

What I tried to solve the problem:

Nothing solves the problem.

PRECONDITIONS:

STEPS TO REPRODUCE:

EXPECTED RESULT:

ACTUAL RESULT:

ADDITIONAL INFORMATION:

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