If you have not seen Anna Zatonskih's 2012 Gibraltar Master Class this puzzle has stymied GMs.

Part 2: How many false checkmates are there and how does Black escape?

Part 3: Can you set this up on a board from memory?

The segment starts at the 25 minute mark.

Very nice indeed! It took me almost 3 minutes which is much for a mate in 1!

Wow, that was very difficult for a mate in 1.

Part 2: For those who find false checkmates. How many are there?

impresive

Part 3: Last test from the Master Class.

Can you set this up from memory?

Indeed nice one. Took me around 3 minutes :O