Hello there @WhoLeb!
Considering that your colleagues are able to access the project with no issues, and your own connection works ok with rider and p4v, then the issue must be isolated to your local setup.
Please make sure that your workspace is properly configurated in UE source control, as server, user name, and workspace should be the same as the ones in p4v.
Next, check that your files are in the proper location, specially the .uproject file, it should be somewhere between your root. Also, make sure your directory path is not very long, as long extensions are prone to cause issues.
As well, checking through the community, there a few scenarios similar to yours. Please check the thread below, and test theris methods for your issue: