I forwarded your message to my hosting company and they replied:

A command to fix any incorrect ownership issues has been run.
Martin Rouf
Rochen Limited

Still no thumbnails. Very frustrating. Can I get a refund?

I had the same problem, what fixed it for me was checking the syntax of the images themselves. eg image_1_test    not    Image 1 test so to sum up no spaces no capitals or dashes etc. Just keep it to underscores alpha numeric lowercase and no spaces hope this helps

Thank you benbear, It's one of the first things I did. So for example, I have my album syntax as:
tldgaweb.jpg
tldgbweb.jpg
tldgcweb.jpg
tldgdweb.jpg
etc.
I presume this is ok.

yes Clawdius they appear to be O.K. so i guess it is back to the drawing board on this one sorry it didn't work it gets very frustrating and shows  how fickle computers can be when one solution works for one and then not for someone else. I assume the bleedin obvious though that the path is pointing to the correct directory or subdirectory if that is the case then i would have to agree that this is perhaps a permissions issue with the server. I know occasionally I have had issues with other components and when i change permissions to 777 (temporarily) on the host I can then get the component to work so it then allows me to work backwards so to speak to resolve issues. i know from your post you say the hosting provider has reset permissions generally though they never set to 777 for obvious reason and so doing this manually helps. (you just have to remember to reset permissions as soon as you have completed your testing)

Again i am making assumptions here - I always have a back up on my own localhost that i play around with when i have an issue like this. Often it works fine on the localhost but not on your live server so that indicates an issue on the live host most of the time. Again i apologise if you have already done or know this I just like to help and share what i can.
 
Cheers

appreciate your comment regarding the naming conventions but how do you explain the fact that they simply don't show in the gallery unless named accordingly. I have tried it on all galleries on my page same result. change them back to having spaces, capitals etc no show. revert back to no spaces etc they show. I assume (maybe wrongly) that this points to something in that would you not agree.

And permissions are certainly not the issue in my case.

Anyway this is not a witch hunt as I said worked for me so I am happy :)

Cheers,

Keep up the good work on a great component.

Clawdius, I'm having the exact same issues as you.  I use Rochen as well. I haven't contacted Rochen yet, but will soon.  In the meantime, if you get this resolved please post the solution.  Very frustrating indeed!

I bought a new gallery (Ignite Gallery) from a different company and everything works fine including the thumbnails. Does this mean it's a SIG PRO software problem?

@Clawdius,
No, it means you had wrong permissions...

to make this plugin work with suPHP add this line to plugins/content/jw_sigpro/includes/helper.php

add to line 229:

chmod($thumbimage,0644);

otherwise plugin leaves thumbnails with 0600 permissions and apache user can't read them.

regards,
Lluís