Which key is Insert on Microsoft Remote Desktop?
I just ran into this issue and had to experiment a bit until I found a solution. Using a Magic Keyboard, I am able to send an insert key by pressing clear to toggle the number lock on (depending on what application you're using, there may not be any feedback), then pressing 0 on the number pad:



I'm not sure if the same trick would work on other keyboards, or how you would do this without a number pad, but hopefully this helps some users.