Bug: Cannot resize PureRaw2 window width beyond 2/3 of screen

When launching DxOPureRaw2 I cannot manually resize the width narrower than 2/3 of desktop. Also saying ‘show windows side by side’ similarly takes up 2/3 of the screen, and in this case other open windows are hidden behind it not displayed in available screen space. It is not obeying Win conventions.

The mouse cursor does turn into the resize cursor when you hover over the window edge but you simply cannot resize it. This is annoying bug and it doesn’t appear to be due to a lot of buttons/menus on the program as there is lots of blank space. I have tried re-sizing width from left or right of the DxO window and also from the corners. You can adjust the height to a small amount, bound by the photo image to process but the width refuses to be less than 2/3 of the screen.

This happens using 1 or 2 monitors, both 4k monitors but different brands/physical sizes. Win 10 latest build 19045.2604

I see DxO photolab has re-sizing listed Dec 20, Resize with a vertical screen. I tried the solution there which was to change text scaling back to 100% but this did not rectify the problem and I need 150% text scaling on a 4K monitor.