cannot save request as favorite

[hype11]

Hi
I using Firefox 63.0.3 with Plugin RestClient 3.0.7 (and f.i. uMatrix).
I would save the request in favorites, but nothing is saved.
I click on Button Favorites/Save current Request and RestClient shows a Tooltip that the request was saved, but nothing appears in Favorites Dialog.
console output while clicking save:
[RESTClient][index.js][btn-save-favorite] get request
{…}
​body: "{test}"
​headers: Array(4) [ {…}, {…}, {…}, … ]
​method: "POST"​
name: "Session"​
tags: Array []​
url: "https://test/"​
: Object { … }

favorite.js:100:5
[RESTClient][index.js][favorite-tags-changed] init
Array []
favorite.js:60:5
[RESTClient][index.js] 0 selected
Array []
favorite.js:127:5
[RESTClient][index.js] favorite requests
Object { }
favorite.js:129:5
[RESTClient][index.js][show-favorite-requests] 0 favorites loaded. favorite.js:155:5
[RESTClient][index.js][favorite-requests-loaded]

[hylkevds]

I also can't save requests any more. And I'm pretty sure I had requests saved, that disappeared.
Firefox 81.0
There is an error on the console:
Uncaught (in promise) DOMException: IDBDatabase.transaction: 'requests' is not a known object store name database.js:80