I noticed this specifically with ancient debris, though it may happen with other blocks without me noticing. When I mine ancient debris sometimes, it appears that no block drops. However when I walk over the area, I can still pick up the block. It may have something to do with the large number of netherrack blocks on the ground (I mine all around the ancient debris before mining it).
Our world is a server running linux.
Thank you for your report!
We're tracking this issue in MC-172142, so this ticket is being resolved and linked as a duplicate.
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