Why no recovery paths were found?

There are probably no synchronized reset paths that originate in the CLKA domain but reset registers in the CLKB domain…which is most likely a good thing :-) I would guess there are 720 setup (data) paths between these domains.

Are you sure you're looking at Recovery Paths? RR usually means Rising to Rising transfers, which would show up in setup/hold analysis.

I don't think that my system has 720 RR paths from CLKA to CLKB, but timequest reports that. So I just to confirm whose are these paths, but it tells me no recovery paths found as well as removal paths, setup paths and hold paths.

I can't do much more without the design(perhaps some screenshots, but not sure if that will show what's going on or not.) I would trust the report_timing reports more than the Clock Transfer reports, but you may want to file an SR or something if you don't get to the bottom of it.

The screenshots shows below, hope it could help:

You just have a single report_timing with the -recovery option shown. What happens if you run the same command(up arrow) and change this to -setup?

Yes, if change it to -setup, it will report setup paths timing.

Yeah, I missed that it was a Recovery Transfer report. Strange. You probably want to file an SR, as it doesn't make sense to me. (You could try making an .sdc file without any set_false_path or set_clock_group assignmnets and run the same commands with that. Maybe the Clock Transfers report is looking at false paths while the report_timing definitely does not.)

Yeah, you are correct.

That still seems odd. As you can see in your screenshot, even false-path transfers get listed. They just have "false path" instead of a number in the table.