I appear to have found a solution:
For folk, like me, who run mostly Unix.
Unzip the file locally, zip it to a new file and use that as your upload.
I have tested thus far:
there is a README.md file in the top folder,
Archive: modx-2.2.12-pl-sdk.zip
Length Date Time Name ("^" ==> case
--------- ---------- ----- ---- conversion)
2910 2014-02-19 14:44 ^modx-2.2.12-pl/readme.md
9212 2014-02-19 14:44 ^modx-2.2.12-pl/core/model/aws/license.md
7522 2014-02-19 14:44 ^modx-2.2.12-pl/core/model/aws/notice.md
7783 2014-02-19 14:44 ^modx-2.2.12-pl/core/model/aws/readme.md
896 2014-02-19 14:44 ^modx-2.2.12-pl/core/model/aws/lib/requestcore/readme.md
--------- -------
28323 5 files
Archive: modx-2.2.12-dr.zip
Length Date Time Name ("^" ==> case
--------- ---------- ----- ---- conversion)
2910 2014-02-19 14:44 modx-2.2.12-pl/README.md
9212 2014-02-19 14:44 modx-2.2.12-pl/core/model/aws/LICENSE.md
7522 2014-02-19 14:44 modx-2.2.12-pl/core/model/aws/NOTICE.md
7783 2014-02-19 14:44 modx-2.2.12-pl/core/model/aws/README.md
896 2014-02-19 14:44 modx-2.2.12-pl/core/model/aws/lib/requestcore/README.md
--------- -------
28323 5 files
As best I can tell it has something to do with the originating system.