In my book (I started using computers during ther Windows 3.0 era), this clearly does not qualify as "working just fine on Windows as it always has", no matter how you spin it.
File Settings > This file come from another computer: Unblock
PowerShell > Unblock-File
Add your smb file share as trusted: Internet Properties > Security > Local Intranet > Sites
I hate it too that you need to sign software that you want to publish. Totally destroys the economics of little shareware type software.