And unless Blynk have updated their code recently it is likely to crash your hardware as any more than 2 or 3 consecutive setProperties doesn’t work, so 24 will cause mayhem.
I think you can use integers there, but mostly I like to use “V0” so I have a visual indicator I’m dealing with a virtual pin, but since setProperty only works with virtual pins… have you tried that?
My code cause crashes of the hardware, so I thought that V0 (V1, V2 and so on…) isn’t replaceable with integer, but … maybe the crash is due to the problem that @Costas refers; and my code would work…