Found it!
The upload file size limit was caused by the default settings in the Suhosin PHP security extension configuration.
suhosin.post.max_value_length and suhosin.request.max_value_length in suhosin.ini
Settings these to 16000000 fixed the problem.
The upload file size limit was caused by the default settings in the Suhosin PHP security extension configuration.
suhosin.post.max_value_length and suhosin.request.max_value_length in suhosin.ini
Settings these to 16000000 fixed the problem.