So the plot thickens…
This happens in an expert world in the cloud that was created 04 August 2019. Definitely created after 1.7 was released.
I was on with a much more trustworthy player last night and they had the same discovery issue. They had joined using an older iPad that they first installed blockheads on in 2014, but then put it away for a while. They dusted the iPad off and updated to 1.7.4 a few days ago and joined the world.
They have 1.6 items discovered but not 1.7 items, no gem blocks for example.
Their phone only ever got 1.7 installed and discovery works properly there. Same for my phone, straight to 1.7.4 discovery works properly.
My iPad first got 1.6 (always had jet packs) and then updated to 1.7 etc. Discovery works properly.
So I think it’s a bug where if a person skipped updates on their device they will get the discovery problem too.
Maybe someone can try my theory on their old device? Please check your version before you update.
(Edit) On second thoughts don’t waste your time. It happened to somebody on iPhone 8 too. There is a bug in discovery. Moving on…