However we may need to upgrade the version of SVN we supply with UE4 on OSX as 1.8.1 seems to have had a number of reports of issues (see here, for example).
Are you able to test a connection to the repository on windows?
I’ve filed a bug report to try to look into the matter.
Yes, it is an issue with the version of SVN we have shipped with UE4. We are looking into upgrading (or possibly downgrading!) the binaries to fix this issue.
Previously we were using the Xcode version of svn rather than providing our own, so you’d need to patch the code and rebuild the editor to use that. For the binary version you can always build your own svn binaries from source for a newer version and replace the svn folder inside the engine directory as a temporary measure - that’s what we’ll have to do. Unfortunately I don’t know quite when we’ll do that. The launcher can open the engine directory in Finder, then you can find the svn folder in Engine/Binaries/ThirdParty/svn/Mac.