both my garmin 500 and 910xt paired with my quarq PM as soon as I turned them on but the zwift pairing cant find it. what do I do?

Try spinning the Quarq as soon as you get to the pairing screen. Also try to pair nothing but Zwift FIRST before the Garmins.

If that doesn’t seem to work, try using a USB extension cable to bring the ANT+ dongle right next to the Quarq.