WPGraphQL Internal server error in console (app.js) + ACF options

When I try to open Graphiql IDE, it doesn’t load (only the loading rotating icon appears). In my console I get:

caught (in promise) Error: Internal server error
at new t (app.js?ver=029d819e2c38c9f70120:30:39347)
at app.js?ver=029d819e2c38c9f70120:30:78333
at n (app.js?ver=029d819e2c38c9f70120:30:32923)
at app.js?ver=029d819e2c38c9f70120:30:32848
at new Promise ()
at Object.then (app.js?ver=029d819e2c38c9f70120:30:32814)
at Object.next (app.js?ver=029d819e2c38c9f70120:30:32933)
at rh (app.js?ver=029d819e2c38c9f70120:30:7097)
at ih (app.js?ver=029d819e2c38c9f70120:30:7610)
at t.next (app.js?ver=029d819e2c38c9f70120:30:8150)

I noticed that the error disappears when I deactivate WPGraphQL WooCommerce (WooGraphQL).

It also has something to do with Advanced Custom Fields’ Options page. When I deactivated it in my theme, the Graphiql IDE loaded as expected.

I also tried removing ACF’s field group assigned to options page – this did the trick, too. On my options page I use Object Field (with post, page and product post types), Repeater Field and some Text fields.

I found this post: https://wordpress.org/support/topic/graphql-interface-not-loading/ and installed GraphQL Gutenberg, although I wanted to disable Gutenberg for the whole site with

add_filter( 'use_block_editor_for_post', '__return_false', 100 );

updated block registry, but it didn’t help either.

I use only the below plugins on my website:

Advanced Custom Fields PRO
version 6.1.4

WooCommerce
version 7.6.0

WP GraphQL Gutenberg
version 0.4.1

WPGraphQL
version 1.14.2

WPGraphQL for Advanced Custom Fields
version 0.6.1

Any help would be much appreciated!