notes field won't update properly: MAAS 3.0 RC1

[webteam-app]

Bug originally filed by billwear at https://bugs.launchpad.net/bugs/1928235

I'm using snap version/build 3.0.0~rc1 on bolla.

I tried adding a note to various machines on bolla, using the MAAS UI.

I can add/edit/delete the note when I'm editing the Machine configuration, but as soon as I save, the note reverts to whatever state it was in before I edited it.

Changing tabs does not help, that is, returning to the Machine list, the reverted note appears in the expanded view.

The only way to make my changes visible is to go back to the Machine configuration screen and refresh. Then my changes appear, no matter how many other tabs/screens I've visited between the change and the refresh.

Anecdotal: I believe if the note was never set, I can set it the first time without reversion. After that, the note becomes "sticky" (like a WORM drive).

Here are the steps to reproduce the issue:

1. Go to the Machine list in the UI of a 3.0.0~rc1 install of MAAS.

2. Choose a machine to edit (the state doesn't seem to matter, i.e., deployed, failed, broken, new, etc.)

3. Go to the Configuration tab.

4. Select the "Edit" button.

5. Edit the "Note" field. (NOTE that if this is the first time adding a note to this machine, things sometimes work as expected, so you may have to add a note, save, and then edit again to see the behavior -- or pick a machine that already has a note set).

6. Hit "Save."

7. The note will revert to its previous value.

8. Switch to the Machine list.

9. Observe that the note for the machine whose configuration you just edited still displays the pre-edit value.

9a. (optional) Visit as many other tabs or screens as you want in the meantime.

10. Return to that machine's summary and select the Configuration tab.

11. Refresh; the Note field will now change to the value you had previously typed in.

I have attached an animated GIF that demonstrates the problem.

NOTE: Per consultation with the MAAS Core Team, I am targeting this but for MAAS 3.0.0-rc1 and tagging it with "ui".