Recovery errors with Time Quest Timing Analyser

Is the signal synchronous to the registers it drives? Meaning, if you do recovery/removal analysis on it and look at the relationships, does that match the clocking in hardware? If it's truly coming in from an asynchronous source, then you should cut timing on it, as there's no point in trying to meet timing requirements that aren't real.

If it is a real requirement, is it on a global or not? You should see clkctrl in the data path if it's on a global. It will also be listed in the Global Signals report.

As for the Assignment Editor, you can make multiple assignments to the node. I'm not really sure what problem you're seeing.