Actually I don’t know what’s happening exactly, but based on WP Core Trac, the export and import of term meta was added in WP 2016:
https://core.trac.wordpress.org/ticket/34062
When I tried an export that included a term with meta, it seemed to work (see attached).
So not sure why the original poster was having problems, but the answer probably could have been “it should work”.
Yay for WP core solving this already!