For anyone else using Microsoft Remote Desktop on a Mac - in my case, I’m running MacOs Sierra 10.12.6 and Windows Server 2016:
There’s always a keyboard mapping issue between Mac OS and Windows, such as " displays @ and visa versa. And CMD \ is needed for a #. I’m using the English UK layout, but the US version is almost identical.
However, I thought I’d found a solution by installing a Mac keyboard layout input someone else had created. It works great, the only issue is # has now completely vanished. So, I would have to switch between inputs if I wish to type a # or put up with the jumbled punctuation/symbol mapping. I guess this isn’t a big issue, since I do most of my work on my Mac. But I’d love to find a solution - everything I’ve tried so far tried hasn’t worked.