What is your operating system?
Windows 11 family 22H2
What is your Shotcut version (see Help > About Shotcut)?
Shotcut 23.06.14 but same behavior on 23.07
Can you repeat the problem? If so, what are the steps?
when i use many mask simple shape and a mask apply on a clip and try to add a text or a transparent on a second track the transparency do’nt work, the add operation break the transparency
see the problem in video here :
Please improve the subject line. Otherwise, people (including developers) will probably overlook it as useless when scanning through the list in the category at a later time. We are rarely going to try to fix a problem as soon as we read about it.
The problem is that Mask:Apply does not reset the alpha channel. That might be a feature for some, but a bug for others. You can see that by hiding V2 and adding a Alpha Channel: View after the Mask: Apply. The, track blender - by design - combines the alpha channels of each video track. The reason the Operation: Add makes a difference is because the Mask filters take a snapshot of the input image to be used with Mask:Apply, and the second Mask: Simple Shape’s input image includes an alpha channel. With the alpha channel view applied, you can toggle the second Mask: Simple Shape filter to see what I mean. The blender in Mask: Apply is alpha-combining as well.
The workaround is to reset the alpha channel on V1 after the Mask: Apply (or on the track) by adding an Alpha Channel: Adjust with Mode = Threshold, Amount = 100%, and Invert ON. I will add a Reset mode to this filter for the version after the next.
understood 
thank
This Mode option was added in version 12.09. However, it clears the alpha channel to all transparent. You still need to click Invert to make it all opaque.