I know that some doubt the value but Lee recommends several things; clean the mold, lubricate the sprue plate screw, lubricate the locating pins/bars, smoke the cavities, and preheat the mold.
Nothing cleans a mold like a can of brake cleaner spray and a few cotton swabs. Without seeing the bullets it’s hard to tell what the wrinkles may be caused by. But the best degreaser has always been brake cleaner. They are totally degreased! Iron molds can start showing speckles of rust in hours in humid conditions.
On all my aluminum molds I use the nickel (silver colored) based anti sieze to lubricate the sprue plate screw and locating pins. A little goes a long way and it does not migrate like beeswax or bullet lube into the cavities. . Never use copper based anti sieze on aluminum.
I smoke my aluminum mold cavities with wooden matches before every session. It’s made recalcitrant molds (aluminum or not) behave more than once and can do no harm, takes little time, and is cheap.
I preheat all molds on a hot plate aluminum or not. It tends to limit a bunch of bad casts. Lee recommends dipping their molds in the melted alloy to pre-heat. Both methods work. I’ve never found it a problem to keep Lee molds hot enough, always the opposite; single, double, or six cavity. Another key is to keep the sprue plate lightly lubed with 2 stroke oil. Lead smeared on the top of the blocks or bottom of sprue plate seems to change venting between the plate and blocks that can cause wrinkles too.
Bad alloy? I’ve so far found it impossible to alloy zinc into my lead. It always floats and gets skimmed off. In 50 years I’ve probably encountered about a hundred pounds of foundary alloy; I’ve kept a new bar of Linotype as a curiosity for 40 years. Everything else has been scrap from who knows where. Boat keels, stock car weights, pipe, cable sheathing, old Babbitt bearings from rail cars, lead from torn down green house windows,range scrap, reclaimed shot, and of course wheel weights. It all cast good bullets, occasionally needing some tin, but otherwise it worked well.
I’m guessing the issue is mold prep from your description, but I’ve be spectacularly wrong before