I noticed that when you change display units from mm to px, the program starts to behave strangely. 

I created a rectangle when I go from layer to object properties (back and forth), the rectangle automatically shrinks (become thinner). 

The solution (which is not) is to leave display units to mm. 

Another thing is that even though you have all units set to px, the Measure tool still displays mm. 

1. Describe your OS (your computer's Operating System: Mac/Windows/Linux/etc. & version).
2. Describe if Inkscape was newly installed, or upgraded from an earlier version.
3. Describe the version of Inkscape and the installer you used (the file you downloaded from the web: .msi/.exe/.zip/appimage/other, PPA/Snap/Flatpak, dmg/other ). 

Bonus points, if you:

• Attach* a screenshot of the issue.
• Attach* an example SVG file that has the issue.

I have Linux, Fedora Kinoite, Inkscape 1.4 fresh install

Maybe this report? https://gitlab.com/inkscape/inkscape/-/issues/5307

Reproduced in Linux Mint, Inkscape 1.4.

Not reproduced in 1.3.2 (Win) because the Object Properties dialog was refactored for 1.4.

Thanks, what now? Are you a part of the developing team and will continue to present the bug to developers?

I'm just one of the mods that "retires" spammers. 😈 

I continue to use 1.3.2 for other reasons. That seems to be the easy way around your situation.

You could still use 1.4 by keeping the display units px and changing the rulers and other tools that have a unit selector to mm (but that is not useful for the object properties dialog).

You can also add your comments and interest in a solution to the report. The level of interest or affected users directly impacts the priority of the bug for the devs.

Thanks, and Linux version 1.3.2. doesn't have this problem?

PS. I thought I belong to "contributors" not "spammers"

I don't currently have 1.3.2 on my Linux partition, but it doesn't have the issue in the Win build.

I installed Appimage 1.3.2 and so far I didn't have same problems as in 1.4. 

I installed 1.3.2 on Mint, no issue there.

Unfortunately, I have to report that there is the same issue. If I want to work I have to set display units in mm, the rest is in px

That's surprising. Did something change from when you used Appimage in comment #10?

One thing I noticed in the original video you shared, is that the scale in document properties was set for 3.77953 with document* units px.  The standard screen/video template is px with a scale of 1. I'd try using the screen template and ensure that px are the document*  (and display) units and scale=1 before changing display units to mm. I would not alter the scale after that... let it update/change on its own if you change the document units or display units..

* "Front Page"

My screen recording is attached.

I did the same first time, I clicked on "Object properties" and not on "Object Attributes", and it worked.  Try Layers and Object Attributes and it doesn't work.

I'm trying to reproduce... am I missing a step?

I recorded it again, and you can see if we are doing something different, or it is just Mint vs Fedora Kinoite issue. Inkscape is AppImage.

Without changing the Front page dimensions, please change the scale in the Document Properties to 1.0 and retry..

Thank you, now works!