You're welcome. In spite of the great helpfulness of this forum, I had to search pretty endlessly to find an answer, and even the otherwise helpful NextGEN people were not about to acknowledge that with some themes (iFeature Pro 4, and now perhaps even iFeature Pro 5 - not tested yet), the upgrades of NextGEN ABSOLUTELY DO NOT WORK. Period. or didn't as of even a month ago.
It had nothing to do with image sizes, as there are preferences that can be set to control the size, and set your own dimension limits.
It.... just ....plain .....doesn't..... work.
So in case anyone else has NextGEN galleries going, and you upgrade to the next release version, and suddenly it all stops and doesn't "see" or upload or do anything - ROLL BACK.
It all stops and hasn't been fixed....for certain themes, that is....past 1.9.1. I can't speak for which themes.....but it doesn't work.
And don't bother with NextGEN customer service. They, like too many WordPress Forum moderator divas, will start by telling you to "disable your plug-ins, one by one, check your server, etc." assuming the fault is yours, and not the version upgrade.
Disabling plug-ins is an often useless enterprise....if you have done it once (definitely do it once) and then rebooted, and the problem remains, it's then an upgrade bug that has to be fixed.
Meanwhile, an added piece of advice I learned the hard way: back up locally often, and thoroughly.