I found that I forgot to rotate back the REFL HWP after the PRC work yesterday.
So, this might be the reason that IFO was not stable in the morning.
Sorry for my mistake.

I implemented the check of HWP angle in the LSC_LOCK guardian (SET_LASER_POWER_NORM state).
If the HWP angle is far from nominal (95 degrees for FPMI), following notification appears:
'REFL HWP angle is not norminal value. Please rotate HWP to 95 degrees.'

So, please manually rotate the HWP if you find this message in the guardian.
HWP can be rotated from the HWP medm (sitemap -> Commissioning Dock -> HWP -> HWP motor calib or sitemap -> SYS -> HWP motor calib).
You need to set total(deg) value for IFO_REFL to 95.