I have no idea what mod conflict caused it or if it was just something in this mod, but between this, its requirement, Space Spidertron, Spidertron Tiers (community updates), Vehicle Grids, Equipment Gantry, Space Exploration and who knows what else out of my list, the vanilla Spidertron recipe got removed from my research until I turned this mod off. I don't really expect a fix because it could be a million different things without knowing what mod caused it, and without an error logged that would be a pain to track down unless someone with a smaller list encounters it too; personally I suspect either Tiers or SE since the first for sure and I think the second move the base spidertron research around in the tree (and i had Tiers' option to move it earlier in the tree on).

I just want to share the WORKAROUND I found for anyone else who encounters this: Turn off Spiderling in Mod Settings. I was able to re-enable the mod and keep the spidertron recipe around by disabling this mod's Spiderling.

Did you try subsequently re-enabling Spiderling and seeing if you still had the spidertron recipe? I suspect that it was probably that anything changing would cause a mod to reset recipe effects and re-enable the spidertron recipe.

Hey sorry about not responding, shortly after this IRL stuff came up and i stopped playing for a couple months, and upon coming back I've since changed up my modlist so much (plus mods updating so much some that were compatible stopped being lmao) that I'm not sure it would be a proper test anymore. If I run into the issue again later I'll see about checking on it though.