P: Synchronization web gallery doesn't work

Hello, the synchronization of Lightroom Classic with the web gallery has not been working for some time now.
The custom order in LR Classic is displayed incorrectly in the web gallery. It worked great for years. What is the reason why it stopped working? What can I do?
Furthermore, there are always a few more photos displayed in the web gallery than in LR Classic. Photos deleted in LR Classic can be seen in the web gallery. I have reloaded the web gallery several times - no change. This is a big problem because the customer sees images that they are not supposed to see. What can I do? Why doesn't this work anymore?
I'm hoping for help because I've been having really big problems with this for about 3 weeks and it's costing me a lot of time.
Thanks in advance.
I don't speak English and I use the translation. I ask for your forgiveness and understanding.
Best regards
Bernadett