I bought 5000 BITB in two lots of 2500 back in March and February, spending around $38 total, IIRC. It's now worth $16 and I haven't received a single sprout in all that time, despite that the wallet has been synced and running more or less continuously on a laptop I set up specifically for running wallets. So, this experiment has played out exactly as I expected based on the amount of money I was willing to put into it... 
You're doing something wrong... or you aren't holding enough coins to allow for sprouting, possibly.I bought over a million coins mid july, and I've been sprouting in batches of 1000 every couple of days ever since. It's held its value fairly well too in the grand scheme of bear market crypto so I'm not down much at all.
Working as intended, I'd say!
Yeah, two key things you did different from me: you bought at a much more attractive price - I was wrong, my average cost was closer to 0.01 per BITB, or $50 total - and you bought way more of it. I have considered buying more over the past few months to give me a better chance of sprouting, but seeing as this project doesn't do anything new or have an interesting use case I haven't bothered.