Bridging will only be triggered over solid fill areas above gaps that meet the minimum area requirements. Please attach your factory file so more of a complete answer can be given.
"A bird does not sing because it has an answer. It sings because it has a song."
I'm seeing this also on certain features where it's not calculating bridging.
I have a 18mm wide gap in a wall that is 4mm wide and the slot is 2mm tall (I'm thinking this is the issue with such a small valley under the bridge). I removed the suggested supports as the bridge area is 2mm above the surface so laying support material in there is a waste This is a slot in the wall for a ribbon cable to come out. (Raspberry Pi Case)
I have changed everything in the settings and this example will not bridge (no yellow coloring). Funny thing is...... it does print ok... not perfect and has a little sagging (I cut that strand out because the first cross has infill between the 2 inner/outer wall lines).
I also discovered another bug during this that I will post separately (Dense Supports will not print with Support Print every-2 layers is on and the first Dense support is between that layer number).
Ok.... Got it to work had to drop the unsupported area threashold way down to 35 and now it's calculating and inserting bridging. Will try print tonight to see if it changes the result.