Z-Flip doesn't connect to Dr.Fone/MobileTrans

I got the Z-Flip in March and at that time I was able to transfer WhatsApp, SMS, contacts etc. from my iPhone Xs to the Z-Flip, using Dr. Fone. I haven't used the Z-Flip since then because there was no belt holster available and I kept on using the iPhone. Meanwhile I was able to find a belt holster which arrived 2 weeks ago and so I decided to update the data on the Z-Flip. There was also an Android-update. However, since these updates, Dr. Fone doesn't connect to the Z-Flip anymore. It recognizes it but the bar gets stuck at approx 75%. The same thing happens when I use MobileTrans (which I think is the same program just different design).
Once or twice I read the note on the phone "connector app needs to be updated" but when I clicked on "update", nothing happened.
Does anyone had/have the same issue and -most important- a solution for the problem ?
Thank you