I have an issue that is identical to this one from 2009:
Fusion 3, Win7 - Remote Desktop Connection to XP Pro - Alt-Tab problems
The very first alt-tab(while keeping alt down, re-pressing alt starts the cycle over again) registers on the remote Windows machine as just a tab, causing me to enter tab everywhere.
I've checked my keyboard settings as described in the original article, but the shortcuts no longer use the Option key, so now I'm lost on what to do.
Alt+Shift+Tab works on the first try, but a decade or more of muscle memory is hard to break.