I had holes in my prints. I also have a BFB printer. A hole or a gape in the material is caused by a lack of filament.
I went almost nuts trying to solve this problem. For me it was a two problem issue. How old is your printer or how much work has it done.
The 3D touch nozzles are .5 mm I would say by now they are much bigger than that. problem 1 is the nozzles wear just like a automotive spry gun wears out it needle and seat.
This is the first thing that contributes to the holes in the object combine this with the main problem, the filament. If you get a piece of your plastic and cut it open length ways you will find at various intervals air pockets. Small vacuum voids as one manufacture final admitted to me when I presented him with hard evidence these voids are vacuum gaps that occur during manufacture. They are not air bubbles.
In most extruder's theses voids are not a problem, As the plastic is heated and compressed to its finial dimensions the voids are compressed out.
However combine the BFB extruder design and a bit of wear, and a lack of plastic at one point here and there and you get what you see in your objects.
You can not do anything about the filament as no manufacture will admit to air bubbles in there plastic.
The solution is to replace your hot end that has longer passage that slowly reduces to 0. 5mm . Any other manufacture will do.
Soon as I did that all gaps gone.
Let me know if this is what your gap problem is? Good luck