New key Sfignature Not Working , Not Recognised

Hi all ,
so I have faced a little problem will writing a song in muse score ,
this song was from : "makam el hijaz" or we can call it "hijaz scale"
in our music we call a "scale" a "makam" ...
this is hijaz scale is an Arabian makam (scale) which

toner : D
key signatures : E♭ , F# , B♭

so I found that I can make my own key signatures as these not listed in muse score
and I have made it but it is not working like muse score can't recognize it
so will trying to figure out the problem
I found 2 problems :

firstly : new key not recognized , well it is ok to make a pdf file with it but as a score it's not working probably , deleting a note then putting a new one not working as the program can't differentiate between Hijaz and C Major (ie. the notes have the same sound)

secondly : while changing key signatures , the program noticed the first note B♭ in the measure and removed the ♭ sign unlike the second one in the measure it didn't remove the ♭ sign ,
however the program is working probably and they have the same sound , but it's not good to make a pdf
so to fix this I just deleted the note then I have put a new one .

So ; did I understood some thing wrong about the program (ie. didn't notice an option or some thing)
or it's just a bug in the program ?

Here is a screenshots of the same notes while changing the keys only
and a score of the test

thanks in advance :D .