core24 - no matching signatures found

```
diabolik@NUC-Ubuntu:~$ sudo snap list --all
Name Version Rev Tracking Publisher Notes
bare 1.0 5 latest/stable canonical✓ base
canonical-livepatch 10.10.3 316 latest/stable canonical✓ -
canonical-livepatch 10.9.0 286 latest/stable canonical✓ disabled
core 16-2.61.4-20240607 17200 latest/stable canonical✓ core,disabled
core 16-2.61.4-20241002 17210 latest/stable canonical✓ core
core18 20240920 2846 latest/stable canonical✓ base,disabled
core18 20250123 2855 latest/stable canonical✓ base
core20 20250407 2571 latest/stable canonical✓ base,disabled
core20 20250429 2582 latest/stable canonical✓ base
core22 20250315 1908 latest/stable canonical✓ base,disabled
core22 20250408 1963 latest/stable canonical✓ base
core24 20250318 888 latest/beta canonical✓ base
firefox 139.0-2 6227 latest/stable mozilla✓ disabled
firefox 139.0.1-1 6259 latest/stable mozilla✓ -
gnome-3-38-2004 0+git.efb213a 143 latest/stable/… canonical✓ -
gnome-3-38-2004 0+git.6f39565 140 latest/stable/… canonical✓ disabled
gnome-42-2204 0+git.38ea591 202 latest/stable canonical✓ -
gnome-42-2204 0+git.510a601 176 latest/stable canonical✓ disabled
gtk-common-themes 0.1-81-g442e511 1535 latest/stable/… canonical✓ -
mediainfo 25.03 40 latest/stable mediaarea disabled
mediainfo 25.04 41 latest/stable mediaarea -
snap-store 0+git.7a3a49a6 1248 latest/stable/… canonical✓ disabled
snap-store 0+git.90575829 1270 latest/stable/… canonical✓ -
snapd 2.67.1 23771 latest/stable canonical✓ snapd,disabled
snapd 2.68.4 24505 latest/stable canonical✓ snapd
snapd-desktop-integration 0.9 247 latest/stable/… canonical✓ disabled
snapd-desktop-integration 0.9 253 latest/stable/… canonical✓ -
thunderbird 128.11.0esr-1 735 latest/stable canonical✓ -
thunderbird 128.10.2esr-1 734 latest/stable canonical✓ disabled
```

Look at core24... i have switch to latest beta. if i try "sudo snap refresh" it's version 1066 installed!

The current stable it's 988 but ever fail install!! Look:
```
diabolik@NUC-Ubuntu:~$ sudo snap refresh --stable core24
error: cannot perform the following tasks:
- Fetch and check assertions for snap "core24" (988) (cannot verify snap "core24", no matching signatures found)
```

I'm current on Ubuntu 24.04.2 LTS... i need to do to fix this issue ?

Start by reproducing `sudo snap refresh --stable core24` on Ubuntu 24.04.2 and compare it with the installed core24 revisions shown by `snap list --all`. Trace why revision 988 has no matching signatures; done means identifying a verified refresh path or documenting the required recovery steps.

Written by the indexing model from the issue text.