Spellcheck button disabled after changing JS Domain

This is my first time posting, and after seeing some other threads in this forum I'm pretty optimistic.

We have a page with the following flow:

1) Upon initial load changes the JS Domain (document.domain) to something different.
2) After JS Domain is changed CKEditor.replace is invoked on several textareas.

After this takes place we notice that the clickable spellcheck button which uses spellcheck.net (not the SCAYT button) appears as disabled within CKEditor. We experimented a bit and found that not changing the JS domain (step 1) seems to correct the issue (button is enabled). It seems to be the only button that doesn't work after step 1

Wondering if anyone here has any ideas as to why changing the JS Domain is causing the spellcheck button to appear as disabled? Will continue to dig but appreciate any help.

Thanks in advance.