Hello I tested and confirmed that file mask is included in search in project too. Tested with current 5.0.4 version.
So wat is your PSpad version? Can you send me screenshot from search in files result? Did you check option in Find in files dialog [x]clear previous search result? -- <https://forum.pspad.com/read.php?4,74399,74401> PSPad freeware editor https://www.pspad.com
