The IR cut filter is a mechanical device and this might correct it; you've got little to lose if it doesn't!
- With camera powered up and video observed, pick up camera and sharply rap it's back flatly on a hard, flat surface.
- Test by covering, then un-covering camera lens to block sensor and exercise IR cut filter.
- If it still doesn't work properly, then step it up a notch and rap again.
- Test again.
- Repeat unless you're ready to float-test* the camera.
*float-test or float check: old US Naval aviation term wherein you toss the faulty device overboard and if it sinks, it's not repairable.
Also known as "BCM-9" (Beyond Capable Maintenance: Navy had only 8 official levels to decide what to do with the device, the aircraft techs 'unofficially' added the 9th level)
EDIT: I assumed the cams are POE-powered and that this occurred to the cams over a period of time and that it wasn't all of a sudden. If this IS, in fact, sudden to this number of cams I would be suspicious of the POE switch's output and/or power budget.