Chords with wrong playback

I am a French user of Musecore 4.0.2
on a iMac 24 Apple M1 Chip with 16 Gbytes RAM . My OS is Mac OS Ventura 4.0.2

When I use chords like "Em7,5b", the playback wrongly use a natural e in the chord instead of the flat e. It means that the chord heard is Em7 and that the fifth is not flat. Somebody has an idea ? Thank you for your help !!
Philippe