UE4 Assertion Failed crash error

My UE4.log

What the crash looks like: UE4 4.24.3 - Album on Imgur

The crash report: LoginId:EpicAccountId:Assertion failed: IsValid() [File:D:\Build\++UE4\Syn -

Does anyone know whats causing the crash exactly? I dont understand the crash report.

It happens every time I launch the editor (check links ^ ), happens on both UE4.24.1, UE4.24.3 and UE4.25 Preview 2 but not on UE4.23 (Unreal used to run fine until last Friday)

I’ve tried reinstalling Unreal Editor itself and reverting a recent Windows update (Theres also a security update that it wont let me revert for some reason, so that might be the cause, tho I havent heard of anyone else having this error so it feels unlikely)

Any help or ideas on what I can try is welcome.

Also is there no public customer support for Unreal Engine, all I have found is a link to getting custom licensing for “custom support and terms” ( Is there really no more publicly available customer support?