Hello, running latest KDE Neon developer dist. and when I: 1) run Chromium 2) push some "Open file" button on website 3) write file into textbox in KDE Open File dialog, push enter 4) it got accepted and then window reappears, until I select file with mouse or click on "OK" button. I'm guessing, problem should be in KDE Open File dialog. This behaviour worked on X11 well.
Chromium is an X11 application. Xwayland on Neon still has problems with such kinds of setups, it requires Xwayland 1.19.