Connectgaps with fill traces

Hi,
I have two traces with missing values (null). i’m using connectgaps: false to make sure that plotly doesn’t connect any missing values (as these should not be falsely interpolated).
I want to fill in the area between the two traces where there IS data, using tonexty:

Unfortunately, what I’m getting is this messed up example:

What am I doing wrong? And is there a way to fix it other than creating separate traces for before/after a gap? this is unwanted as the ammount of gaps is large and this will result in tons of traces.

Cheers