@haydrionrayel – “PHP 7 is not problematic” – Quite to the contrary, the issues we are seeing here are CAUSED BY BUGS IN PHP. PHP recognized and fixed the main bug in 7.0.26 and 7.1.12 already. You can see our other post about this for links to the PHP site and discussion and patching of the bug by PHP. There is yet another PHP bug still present in 7.2.0.
And the bug in PHP were/is affecting systems well beyond NextGEN Gallery. Your point might be that many plugins aren’t affected by the PHP bug. That’s generally true, and great. But that doesn’t change the fact that the issues are are the direct result of a bug introduced in PHP that breaks some of PHP’s core logic.
Also, to clarify: there are only a few specific versions affected here, not all of PHP 7. It’s PHP 7.0.26, 7.1.12, 7.0RC6 for the main bug. 7.2.0 has a secondary bug that affects fewer people, but still has similar symptoms. Other versions of 7.0.x and 7.1.x work fine.