There are many reasons why this can happen, and it depends on which version control system you use. For both git and svn, the problem may be ssl root certificates. You need to add root certificates from your keychain to the ssl configuration.
See this post for more details .
If the problem is not related to the SSL certificate, most likely it will be a timeout problem when you get the original repository, if it is very large. View integration logs for more information.
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