Can no longer create a repo on local git-server, due to certificates detection

[tiptronic]

I can no longer create a repository on my local Git-server. Kactus complains about the self-signed certificate (although this is trusted in my certificates-keychain)

It then shows the certificates dialog and exits with an error:

If I create the repository in another application (e.g. Tower), everything works find and Kactus does use it properly without further complaining.

Everything on MacOS 10.13.3 (17D102)

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Btw: All active buttons get white on hover: