"Back to top" gets cached in only one language on multilingual site

When using the TOC Filter on a multilingual site, if you translate "Back to top" using the Translate interface (admin/config/regional/translate/translate), the content on an any individual node will be displayed with whichever language was loaded first after clearing the cache.

We are using Entity Translation for managing translations. Caching is disabled under Performance.

For example,

• Create a node and enter content with [TOC] and headings
• Enter a translation, also with [TOC] and translated headings
• Clear the cache
• View the node in one language
• View the node in the translated language
  • The "Back to top" here will be displayed in the language you first loaded
  • The remaining content is translated properly

I attempted to disabled the cache in hook_filter_info() in the toc_filter module (line 43), but it had no effect. Is there someplace else that this might be getting cached?

Any recommendations on how to tackle this?

Relevant enabled modules:

• toc_filter
• entity_translation
• i18n
• i18n_string