Apple updates seemed to have knackered some Ant+ connectivity on iPad and iPhone…Trial and Error has gotten me to these solutions…one of these does work depending on your actual issue.
plug lightening cable or 30 pin connector to Wahoo Ant+ dongle into iOS device before opening Zwift app on iOS. If you get “the accessory is not supported” press ok and carry on
If Ant+ icon doesn’t show on the paired devices page, then wait 2-3 minutes, sometimes it just shows up.
If 1-2 don’t work, on paired devices page press Let’s Go anyway (still with Ant+ dongle connected) - or Skip…ultimately you want the “paused page”
On the paused page in the right column select PAIR, this takes you back to the paired devices page and the Ant icon should now be pulsing next to BLE icon.
I’ve spoken to Wahoo about this and their position is Apple with 11.2 have done something detrimental for the Wahoo dongle and they are working on it together
Hope this helps…its saved me no end of time pre workout