"I don't understand this - if it's unsolvable, why post it?" as said by Tuffty19.

Solved this by quessing and got lucky. Tens are R5 c1-10 R8 c13-22 R14 c1-10 and R19 c13-22, then cloud shape upwards from the tens.

Total guesswork - thank you Lucy for the hints; I would never have been able to solve it otherwise.

It is a really easy guesswork.
You can divide the puzzle to 4 squares. All of those contains the exactly same (cloud shape) object (but not in the same row).

Put the zero lines in and it's easy guesswork.