Editing a table at nowiki (Tabell-test) in Firefox is not possible anymore. This bug has emerged quite resently, possibly this evening.
It is not possible to set the cursor inside the table, but it seems like it is possible to paste stuff into the table. If the table cell is selected and I start writing the text emerge and the cursor is visible. It is not possible to edit existing content, it will be replaced.
Checked in both Ubu and Win10, and the bug is only visible in Firefox. There is a somewhat similar bug at Wikidata, T123229.