What do you have in the latest post that is not found in previous e.g. attachments, special markup or styles?

Sorry about the delay in replying (A bunch of things coming up all over).

Anyways, after varying a bunch of posting attempts, the following pattern came to light. When the post had no images, it posted just fine. When it had an image inserted as a link, it posted fine. It was only for posts trying to upload image files from a local machine that brought up the

metaWeblog.newMediaObject method
received from the blog server was invalid:

response.
So, any thoughts on possible causes and solutions?

I guess this method is not implemented in b2evo yet.

I solved it this way (in version 4.1.2):
Goto /blogs/inc/xmlrpc/model
Edit the file _xmlrpcs.funcs.php
In function function _wp_mw_newmediaobject
you will find a comment saying: // Avoid problems
and the second line after this comment is:
$rf_filepath = preg_replace( '€[^a-z0-9\-_./]+€i', '-', $rf_filepath );
Comment out this line.
I am not sure what preg_replace is intented to do, but what it does is blanking out the filename.