Dom0 log of qvm-open-in-vm parameter for debugging? (trying to debug qubes-url-redirector)

I’m trying to debug qubes-url-redirector (in which “open in disposable vm” does not work on 2 out of 3 computers). I believe qubes-url-redirector calls qvm-open-in-vm. Does
dom0 log somewhere what parameters get passed to qvm-open-in-vm whenever it gets called? grepping through /var/log/* and /var/log/qubes/* did not return anything that looked relevant.

The qubes-url-redirector problems I’m trying to track down is documented in:

Also, documentation of a more serious issue that happened at the same time is in: