IMAP ESEARCH (for text) broken

It seems that fairly recently, Zoho's IMAP server started advertising ESEARCH capability.

And it's broken when trying to use it for text searches (with a "literal" representing text):

<tag> SEARCH RETURN (ALL) CHARSET US-ASCII TEXT {16}

Server then says:

BAD syntax: expecting 'c', found 'h'

This works though (non-E SEARCH):

<tag> SEARCH CHARSET US-ASCII TEXT {16}

And this works too (E SEARCH but for unread messages, not text):

<tag> SEARCH RETURN (ALL) UNSEEN UNDELETED

Since the server advertises ESEARCH, the command to search for text (the one failing) should work too.

Further info: