Might have been too technical here, but OHCI and EHCI is different. USB controller being detected as OHCI controller works, where when it is detected as EHCI it doesn’t, saying that the IRQ in question was never polled, and stating that a kernel option should be specified to make it polled manually, otherwise that IRQ is being deactivated, which seems to result into your mouse to go undetected. Makes sense?
@confused has a point. Kcma-d8 and kgpe-d16 being really similar, looking at HCL reports, with coreboot/libreboot tells us that they were functional with libreboot release. I do not see HCL reports with Asus firmware there. They were both reported with 2016 release of libreboot, either by Timothy or Vikings. The new HCL report is on a different version of Qubes as well, meaning its a whole different test case (Xen and kernel being different).
You might want to add irqpoll kernel option as suggested. But as of now, the reason why that USB controller is detected non consistently as OHCI/EHCI seems to be the visible cause of the behavior observed.