Sync of Large Media Files fails with 'push failed: xxxxxx:test.zip parse error: not well formed

[xiccarph]

I have dokuwiki (currently 'Binky') installed on my home network, and a manual installation (currently 'Binky') on my domain hosted on bluehost. Both installations work fine.

I have synced successfully many times from the 'local' home network wiki to the 'remote' bluehost wiki. I did recently upgrade to the 2013-12-08 Binky release.

I have a number of large media files (20Mb - 30Mb) that I have uploaded to my local installation. I have php values configured properly to allow the large upload/post file sizes, as well as having had to adjust the memory_limit setting upwards to allow the upload of these large files. All of the large files are zip files (zipped up firmware binaries). The files were zipped on an Ubuntu 13.10 system.

Using the previously functioning sync profile, smaller media items and pages sync fine. Other, smaller, zip files sync correctly as well. I set an extra long timeout (120s) on the sync profile, but the large zip files always fail to be pushed to the remote system and show an error:
push failed: xxxxxx:test.zip parse error: not well formed

No error is shown in the php 'error_log' which is written to the {dokuwiki}/lib/exec folder where the remote sync php files reside.

I could easily be missing something obvious, so any advice about how to further narrow the search of what is going on would be welcome.