Cannot create super table elements

[laurabennett]

Description
I can add fields to my super table from settings but not from field manager

Steps to reproduce
New install with Field manager and Super Table
Open field manager
Create a new field, select super table
Click + new field within the configuration table and nothing happens

Additional info

• Plugin version:
  Field Manager | 2.1.8
  Super Table | 2.6.2

• Craft version: 3.5.8

• Multi-site: No

Additional context

[engram-design]

Strange, can't seem to replicate this behaviour: https://d.pr/v/b6jeQe

Any JS errors when you click "+ New Field"?

[laurabennett]

I see a JS error when I go to field manager but nothing new when I click +.
I can add child fields to a matrix but that has a popup so works slightly differently.

Uncaught TypeError: Cannot read property 'content' of null
at r.initSeoTitle (:1:33521)
at new r (:1:33386)
at :61:1
at m (jquery.js:129)
at Re (jquery.js:6128)
at b.fn.init.append (jquery.js:6264)
at Object.appendFootHtml (Craft.js:1444)
at s.constructor. (field-manager.js:363)
at Object.o [as success] (jquery.js:10771)
at u (jquery.js:3496)