Additional Variants not saving

-- HikaShop version -- : 4.0.0
-- Joomla version -- : 3.8.13
-- PHP version -- : 7.2
-- Browser(s) name and version -- : Chrome

I've got a product with two characteristics, with a total of 30 combined possible variants. However, one particular combination of variants will not save no matter what I do, leaving me with 29 variants actually saved. (The one missing is Mens 3X/Womens 2X.)

I hit the Add button, select the characteristics, and hit save. The page refreshes, but no variant is added. No error is given. Just nothing.

Any idea what may be happening?

Update: Never did get it to save a new variant, but I deleted all variants and had it auto-create a new list. That worked.