Indentation setting reverts to default when switching away from document

[pbarney]

NppToolBucket version: v1.10.6622.41336
Notepad++ version: v8.6.7 (32-bit)

Issue: when changing the indentation settings (either via toolbar or alt+shift+I shortcut), settings do not stay when switching away from the document and then back to it.

This happens regardless of the tab settings of the language in the NP++ preferences (Settings → Preferences → Language → Tab Settings (on the right-hand side))

For example, suppose you're editing an HTML document that NP++ has set for 4 indentation spaces. If I set it to 2 via the NppToolBucket plugin, it will work until I switch to a different document tab. When I return, the indentation settings have reverted back to 4 spaces.