The reagent count on spells has been missing from my bars for some time. It reappears if I roll back to the 12/15/19 version of Bartender 4 for Classic.

I logged in to Classic just yesterday and counts on my soul shards are showing perfectly.

Can only recommend to confirm you are actually using the classic version of the addon, because the retail version will actually work, but lack classic-specific functionality like adding the reagent count, which Blizzard disabled for classic.

Thanks for the super fast reply. I went back and checked addons to see what it might be. It wasn't working originally so I rolled it back but then I just upgraded back to current and it is working now. I'm assuming it might have got swapped out for the retail version at some point.