File managers don't show image thumbnails from smartphone although set Yes

[Dan-cer]

Distribution

Mint 21.3; LMDE 6

Package version

6.0.4

Graphics hardware in use

Intel Corporation CoffeeLake-S GT2 [UHD Graphics 630] (prog-if 00 [VGA controller])

Frequency

Always

Bug description

Images from smartphone via MTP or PTP have no thumbnail preview in Nemo, Nautilus or Caja, although the setting for external sources is "always" with the highest max. size option available.

Steps to reproduce

1. Plug in smartphone via USB 3.
2. Set to file transfer in smartphone (or foto transfer)
3. Open directory in file manager
4. In .../DCIM/Camera/ there are no thumbnails visible.

Expected behavior

As I set in Nemo (Caja, Nautilus) settings thumbnails preview should be active and visible.

Additional information

I know that this issue started with LM 21.x while I still preferred to stay on LM 20.3 where thumbnails from smartphone are displayed well.
I mostly use Nemo. However, to get the issue addressed rightfully I tried other file managers too. And I found out that it is more of a Cinnamon or even Mint issue.
Because LMDE isn't based on Ubuntu, we can't blame Ubuntu for it, right?
The following screenshot illustrates that it is very difficult to identify any image as their names are nearly identical bc made of timestamp: