Can't push NuGet package containing winscp.exe (WinSCP 5.15.9 dependency)

I’ve successfully pushed many nuget packages to my package registry. However, I’m having issues with pushing one. The difference with this one is that it contains an .exe file from the Nuget package dependency on WinSCP v5.15.9. This allows us to SFTP (which does not have native support for). I’m getting a BadGateway response, but i’m guessing that’s more of a generic response to rejecting the package.

My company runs their own instance of gitlab.
We’re running GitLab Enterprise Edition [13.12.15-ee]