Interaction with Mac running Windows programs

We have several customers that use Mac's, but are running our Windows application using something like Bootcamp, Parallels and sometimes Windows Remote Desktop into a terminal server. When I remotely connect into their Mac OS, when they bring up the Windows program, if I try to type... the only character that appears is "a". So, for instance, if I open Word for Windows and type in "hello", instead I get "aaaaa", which obviously doesn't work very well!

The only solution is for the customer to allow remote access from the Windows side of the computer.

To be frank, GoToAssist has the exact same issue, but I was hoping Zoho would have overcome this. Have you heard of this before, and do you have any solution? I am looking to dump GOTO, and I am hoping ZOHO Assist is the solution.