v155f php7.1

I am having a problem with adding Structured Data Markup code in a middlebox - when I add the code the box disappears completely, i.e. not just the text but the space the box consumes. The code is the whole html 'document' as marked up using Google Markup Tool.

(possibly unrelated however something I have encountered for a while now has been the non acceptance of header title codes higher than h4, i.e. h1,2 and 3 results in the text between <h> and </h> disappearing altogether - not important as the above, just thought it worth mentioning)

any assistance would be appreciated.
cheers,
Mike