Sims won't try for baby

I solved this issue for myself. It turns out that in my instance it has nothing to do with damaged game files, custom genders, or pathing issues. I just forgot that one of my mods did a thing, and the inconsistency between my interaction menus (see below) caused me to assume there was some kind of bug.

I forgot that with the Personality Please! woohoo limiter package, any Sim will not Try For Baby if they are not Married or at least Engaged to their intended baby-making partner.

Interestingly, while any Try For Baby options will not appear when interacting directly between the Sim and their unengaged/unmarried partner, the options are still visible and appear to be selectable when interacting with relevant furniture (beds, showers, rocket ships, etc.) - and that really tripped me up.

However, while the Try For Baby options appear to be selectable via the furniture itself, doing so will still not ever trigger any interactions between the Sim and their partner until they reach at least an Engaged relationship status. Selecting these options before your Sim is respectably committed to the other individual will simply cause... nothing to happen. Not even an action in the Sim's queue.

Initially I thought this was because one of my Sims had the Proper trait. Boy do I feel dumb now.

TL;DR:

Double-check if you have the Personality Please! mod, and the woohoo-tryforbabyrestricted package file. Then make sure your sims are at least Engaged, or remove the file.