Thanks for digging into this @charlie.brooker and @hmurya .
I feel pretty confident that Ladybug is doing a faithful interpretation of the EPW data but I still have a theory of what could be going on here.
I have seen some EPWs were the weather station source does not actually have wind direction data and, instead of using the EnergyPlus missing value of 999 (like they are supposed to), they use a wind direction of 0 or 360 for north. So it’s possible that Clima is using something implicit to determine that certain hours don’t actually have wind direction data and it’s therefore discounting them in the resulting wind rose. Maybe it’s that certain hours have a direction of 0 and this is (or is not) supposed to be counted as “real” data while a direction of 360 is (or is not) supposed to be treated as missing data.
If we can figure this out (and ideally confirm with the Clima people that this is the assumption they are using), I would be happy to add some options into the LB WindRose component that will try to discount these hours. Actually, you can probably already test this now using a conditional statement_.