THANKS! Since the grout definitely doesn't belong there, I'll chip it out and inspect the pipe & flange to confirm whether they are properly connected. There's no sign of a leak yet so I think I caught it in time (The joys of a pre-owned home...)

Toolman Rod, it's hard to tell from the photo, but I don't think that drain looks like the 3 piece drains for tile-in. The 3 piece drains allow water that weeps down below the tile to migrate back into the drain via the shower liner, sort of like a secondary drain.

Do you see any screw threads at the bottom of the drain body? Break away that grout to see. BTW, the grout is not supposed to be there.

Tile guys are known to do hack plumbing jobs. If this shower job is newer I would really investigate this. At my old house the shower leaked into the adjacent closet after about 3 years of living there. I busted the tile and found out the tile guy just used the same cast iron drain and tarred around it to bond the PVC liner!

Watch this video on how the whole system is supposed to work: https://www.youtube.com/watch?v=EuChTwnHWvU

THANKS! I'll post an update after I remove the grout to get a better look. Your concerns are consistent with other "workmanship" issues I've discovered here.

I suppose you can get a better view of the pipe connection by using an inexpensive "inspection mirror."

I encourage you to do a fill leak test: plug the pipe hole with a test bladder and fill the shower with water and wait a few hours. Installers are supposed to do this test after the liner is installed to check for leaks. There are lots of videos on doing this.

Is this over a slab or wood floor? In any case, leaks mean complete redo.

Good Luck.

It's over a crawl space -- 70 feet in! Your ideas on further testing before I crawl under to inspect from below are very useful!

Here are the photos with the grout removed.

There is at least a 1/2" vertical overlap (top flange stem within the lower cup), maybe more -- that's all I could feel with a curled finger, since my mirror was too big to insert. This seems like the type of secondary drain you described. No threads are visible. Could the grout have squeezed down from above, indicating that a serious backup from below might seep under the tile? It really makes no sense as an intentional fill, but who knows what the guy was thinking! At least this doesn't appear urgent since a gravity flow should be contained by these pieces.

Footnote: The drain now drips loudly after shower use, since there is a vertical separation inside the cup, plus an echo. I wonder if some well meaning novice added the grout to provide a quiet "trickle path" much like folks hang string to silence dripping faucets? At least that could explain the decision. (The drip noise doesn't bother me.)

Yes, it does look like a 3 piece drain. A backup seeping down under the tile will not occur because the shower liner is the real watertight plane.

They are supposed to put a fair amount of pea gravel around the drain before they pour to mortar slab, so that water that migrates down has a way to drain through the gravel (instead of solid mortar.)

Unfortunately, there's no way of knowing if the proper details were executed correctly after the tile is installed. Even worse is that leaks go undetected and can likely cause much more damage to framing.

Thanks again. This gives me some peace of mind. I'll try to do a subfloor inspection the next time I'm in the crawl space to ensure there's no evidence of a problem. (I just didn't want to have to do major work in those cramped spaces!) You've been EXTREMELY helpful!