Good question
ARX awards seem to be transactional - some round up, some don't. So if you handed in 4 bounties and all were < 200k they may all have been rounded down to zero. There is an option to hand in all at once, sounds like there's more work to do around this.
(I was looking at PAX missions yesterday and it seems that if one pays < minimum you get 1 ARX - the opposite of what you're seeing for bounties. This doesn't mean you are wrong at all - ARX awards seem very ... bespoke. And they get changed, so you may just be seeing a new rule
).