Hey @jeroenverplancke – Few quick thoughts.
1) You can download older versions from the Advanced page here: https://www.ads-software.com/plugins/nextgen-gallery/advanced/
2) I want to emphasize that so far today, we’ve had over 80,000 downloads of the new update, and a grand total of 7 support tickets. Of those, one had nothing to do with the update, and 2 were caching. That leaves 4. I know it doesn’t help you at all, but as far as a big update goes, that’s actually quite solid. It means the update is working very well across almost our entire user base. If there were widespread issues, the forums here would be blowing up.
I mention all this because it’s likely your issue is very specific – server side caching, theme/plugin conflict, etc. It may be a while before someone else finds the issue, which means whatever it is, it will stay broken for you.
3) With all that in mind, we’d love to troubleshoot what’s happening with your site. If you are open to it and willing to send creds, I’ll look at it myself this evening. Just submit a report at https://www.imagely.com/report-bug/ with site details and put “For Erick” in the subject line so I see it.
If not that, if you’re willing to provide any more details on what you’re seeing – especially screenshots, I’d be happy to provide whatever input I can.
It sounds like you just want to get working. If so, I totally understand. You can still grab the last version from the link above and downgrade, and try again once we’ve got a couple more 3.0.x versions out.
Thanks.
Erick