I am having pretty much the same problem, too.
The plugin just got all glitchy. Can’t edit anything within a plugin–title, code, description…nothing. Hitting the Save button shows the “plugin updated” banner like you successfully did, but everything just shows/reverts back to what was previously there.
The Snippet list is also glitching. You can toggle an active plugin to inactive, which fortunately does deactivate the plugin, but upon refreshing the page it shows the toggle as active again (plugin is still deactivated, though, as far as I can tell).
Can’t delete any snippets either.
Can’t change any settings, either–they all revert back to the setting it was previously at.
