Comment 218 for bug 1870736

i can observe no fractional scaling on a default installation dell xps5790 even with a single monitor (4k). similar connecting a second monitor is not working separately either.
I tried different display resolution to no avail.

I eventually started changing the display resolution and gave up on fractional scaling.

nvidia 450
libmutter-6-0:
  Installed: 3.36.6-1ubuntu0.20.04.2
--------
xrandr program version 1.5.0
Server reports RandR version 1.6

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lspci
00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 630 (Mobile) (rev 02) (prog-if 00 [VGA controller])
    DeviceName: Onboard IGD
    Subsystem: Dell UHD Graphics 630 (Mobile)
    Flags: bus master, fast devsel, latency 0, IRQ 176
    Memory at eb000000 (64-bit, non-prefetchable) [size=16M]
    Memory at 80000000 (64-bit, prefetchable) [size=256M]
    I/O ports at 4000 [size=64]
    Expansion ROM at 000c0000 [virtual] [disabled] [size=128K]
    Capabilities: <access denied>
    Kernel driver in use: i915
    Kernel modules: i915

I found the prime-select toggle and set it to intel...
same issue