Unsaved tags are cleared when toggling gif animation

[IonoclastBrigham]

Repro Steps

1. Open a GIF
2. Edit or enter one or more tags in the main tag bar
3. Without saving, toggle the View > Animation menu (either on or off, it doesn't matter)

Expected Outcome

Animation should just toggle on or off, allowing the user to continue editing their tags.

Actual Outcome

All unsaved tags are lost.

Notes and Commentary

• When it happens, the tag bar is left in a selected / modified (gold) state, but all edits are gone; could be a clue as the the cause.
• With the above repro steps, this bug is observed on my machine with 100% reliability.
• This behavior is not observed when toggling the Animation menu while editing tags for raster images; probably also a clue.

System Info

Ivy v2.3.1 on macOS 10.14.