I have a number of locations, a lot of them, that I'm using.
So, if I have a product with 4 variations, I can end up with about 60 difference inventories. This should be fine, save for a bit more work on my end, but it becomes impossible to save any further inventories under a product after you hit about 40. Maybe my database isn't liking the loop of updates every time I save to add an additional inventory?
I've had to combine inventories, doing multiple locations on an inventory, to resolve the issue and have less inventory sections.
Not sure what the fix would be, but the addition of each new inventory slows up the saving process until it finally can't save anymore.