Our slideshows are not working (on an iMac OS version 10.12.4 using current versions of Chrome and Safari) and I don't know why.
However it looks OK in Firefox.
It sounds like you're running into a problem displaying Adobe Flash content in certain browsers.
(If there was a problem with the gallery itself, the issue should be present in all browsers.)
Even if Adobe Flash Player is not enabled in a browser, you should still see the Mobile Player version of the gallery, though.
Unfortunately, certain browsers are starting to block Flash content by default and it's becoming more and more difficult to view Flash content on the web. Please see this blog entry entitled The End of Flash and What this Means for SimpleViewer for more information.
If you would like to try to re-enable Adobe Flash Player in Chrome, please try the following:
(1) Open Chrome
(2) Click the 'Options' button (the three vertical dots near the top right)
(3) Select 'Settings'
(4) Scroll down to the very bottom
(5) Click the 'Show advanced settings...' link
(6) Scroll down to the 'Privacy' section
(7) Click the 'Content settings...' button
(8) Scroll down to the 'Flash' section
(9) Select 'Allow sites to run Flash'
(10) Click the 'Done' button at the bottom right
Please see this web page for similar steps for Safari.
Hopefully this will help. However, please note that visitors to your web site might have to do the same, otherwise they may just see the Mobile Version of your gallery. Unfortunately, there is no way to control user's browser settings (to ensure that Flash content will always be visible) from within the SimpleViewer gallery or its web page.
In my Plugins, I see I have WP-SimpleViewer Version 126.96.36.199 but there's no alert to Update.
On your WP-SimpleViewer Wordpress Plugin page it says the current version is 188.8.131.52
The current version of WP-SimpleViewer is, indeed, v184.108.40.206 (but the most recent version published to WordPress's own plugin repository is v220.127.116.11, which is why this is the latest version listed on the plugin's page).
If you like, you can download v18.104.22.168 from our own WP-SimpleViewer support page.
I do not believe that it will make any difference to the Flash related problem you reported but several bugs have been fixed since v22.214.171.124 (please see the plugin's Version History page for details) and it might be worth upgrading anyway. Just follow the Installation instructions (overwriting your existing WP-SimpleViewer plugin files). Don't forget to reinstate your Pro 'svcore' folder afterwards.
Have I somehow lost my Pro status?
Just to clarify, your galleries are still SimpleViewer-Pro. You'll know if your galleries are SimpleViewer-Standard as there is a SimpleViewer badge/link in the lower right corner of all Standard galleries. This branding is not present in Pro galleries.
In light of the slow demise of Flash, you might like to take a look at our alternative HTML 5 image viewer: Juicebox (which does not use Flash at all). Check out the blog entry (link above) for more information (and details of a 30% discount for existing SimpleViewer-Pro users).
There is a Juicebox plugin for WordPress, too: WP-Juicebox. There is no automated way to convert WP-SimpleViewer galleries to WP-Juicebox but the WP-Juicebox interface is very similar to WP-SimpleViewer so it should hopefully not take too long to recreate your galleries using WP-Juicebox. (Your images are already in place and WP-Juicebox displays Media Library images attached to the post containing the gallery, just as WP-SimpleViewer does.)
SimpleViewer Support Team