I have emailed wowslider support and waiting on an answer.
Will let you know when I get a response.
For what its worth it does work but I only started getting this problem when I updated to Version 7.5 of wowslider. Plugin is Version 7.4 with latest updates ( as of 26-01-15)
I reverted back to Version 7.4 of wowslider and everything works ok again.
I am using the import from folder method.
Convinced there is a problem with the zip file creation in Version 7.5 so
I will also email wowslider support but won’t hold my breath based on past experience.