LSB not showing up on ACF Options pages

[filtah]

Hi all, The LSB is not loading on ACF options pages.

The 2 latest releases (3.12.1 ans 3.13) have this problem.

In addition, if you check the checkbox "Display language tabs" on the ACF tab under Languages, the tabs appear but are non functional.

The option page is added without any arguments, by simply calling acf_add_options_page(); from the theme's functions.php

I've tested ACF versions 5.12.3 and 6.0.6 both of which have the same problem.

So looks to me like the problem was introduced with changes to the ACF module in the 3.12.1 release.