My druid can't use the recommended azerite power

My character has a recommended azerite power only for healers. Fungal essence is not available for druid tanks. It is located in the head slot.

This indicates that you have Resto as a higher priority in your setup. If that isn’t the way you intend it to be you should change it.
On the left of the Best in Bags screen there are options for specs, read the instructions underneath that.

If it still doesn’t do what you expect provide us the WoW addon export string and we can recreate what you’re seeing.