OWA Agent 1.6 - not working after 6.2 upgrade

We had OWA Agent 1.6 working fine with Fortitoken Mobil and Fortitoken 200 HW on version 6.1.2-build 420

After upgrading to version 6.2 build 542 - the OWA Agent stopped working for all users.

The Logs or Debug Logs are not very informativ. 

2020-09-24 13:07:51,268 - REST API - information - Receiving HTTP POST request at "/api/v1/auth/" from "192.168.xx.xx": (API user=apiuser, username=xxxxx, token=573726)
2020-09-24 13:07:51,281 - REST API - warning - Invalid realm is replaced by 'myrealm'
2020-09-24 13:07:52,307 - REST API - warning - HTTP POST request from "192.168.xx.xx" failed for "/api/v1/auth/": User authentication failed (Response: HTTP 401, API user=apiuser, username=myrealm/xxxxx, token_code=573726)

I Have tried the same login with an API tester, without any problem.

I Created a new user and assigned a Fortitoken HW, then by magic it worked.  But I cant see any difference between the new user and all other remote users.

Any ideas here ? How to troubleshoot ?