Thanks for your fast reply.
I've just tested something. The blocks are still mined and are just marked as "???". Selling all, mining a bit and selling again shows that some are mined. I guess it has to do with the "New block mined" feature added in the recent patch that turned all previously unlocked blocks to "???" because they don't exist as "mined" in the new object/array. As soon as a duststorm hit I had Top Soil "unlocked" again and became visible in the blocks section.
Yes, I know that 969 is the current end block but meteors dropping shards on 969 fields makes it impossible to pick them up currently. That's what I meant.