Not sure… Could be that filter is only looking at the start date of the date property,.
You can add the filter here to make a first selection AND in the filter before the next module to filter out any incorrect ones that were selected because of the end date.
another workaround could be to add a column in Notion where you extract the start date with a formula and use that column in the filters in Make.
A tip to get the formulas correct for the filters: use a “Set multiple variable” module to test the output of the different formulas first. If you have the formulas correct, you can add it in the filters to check if Notion is making the correct comparison/test or if you have to adjust the operator you use.
Sorry as I am a newbie here I could not answer more than 18 times the same day…
I need to figure out which date the filter in the module is filtering and test your method.
The goal of all this is to avoid adding a property in Notion and keep my DB clean, but is this relevant, I don’t know.
And another goal is not get all records with the Notion search module…
Thanks anyway, any other idea appreciated 
I have to learn this one, I’ll do some tests and feedback here. Thanks.
I have removed the filter for the status in the filter and moved it to the Notion Module. It had a space or something like this and didn’t work.
Actually I think it’s working now !
Thanks a lot to @PierreL, @AutoPilots and @Philippe_Billet for your help.
Cheers from France
Hello there @CharlyMoriaud 
It is amazing to hear that you were able to crack this with the help of @AutoPilots, @PierreL, and @Philippe_Billet! 
Thank you very much for updating us along the way!
PS: I marked your last comment as a solution to keep our community organized and neat for others.