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Directory write protected ONLY when using Remote Desktop?

I have a remote computer that I access from my computer using Remote Desktop. There, I can read/write/delete files in a certain directory.

If I share that directory, then access it via my computer, and provide the same credentials used for accessing via Remote Desktop, I am limited to read access.

The account used for both Remote Desktop and for accessing the share is an Admin account. Just for good measure, I even gave the User account full access.

Specifics:
Both my and the remote PC are running Windows 10.
I’m running Remote Desktop/sharing on a VPN provided by ZeroTier.

To the best of my knowledge, accessing the directory should have the same behavior regardless of whether doing so via a share or Remote Desktop. Am I wrong? If not, what should I look for?