This is like the scene in A Few Good Men where Tom Cruise asks where the mess hall is. The list you show in your screen shot isn’t necessarily exhaustive (and in this case we know it is NOT).
To the extent that your complaint is that three Rare Ascension Materials (farmable or non) is not sufficient reward, I agree with you.
But stating this as a bug is incorrect. It’s been this way for some time and everyone who’s done research on it should know that. Here’s a reference thread. I’ll quote the relevant text, emphasis mine:
The options that you can select one of currently appear to include:
Your choice of 1 of 2 random 4* Ascension Material selections (e.g. Poison Darts OR Mystic Rings)- Your choice of 1x 4* or 3x 3* Ascension Material selections (e.g. 1x Farsight Telescope OR 3x Warm Cape OR 3x Battle Manual — farmable 3 Ascension Materials can currently be included as an item choice)
- Your choice of 1 of 2 random
50x30x Titan Battle Item selections (e.g.50x30x Hurricane OR50x30x Time Freeze) - You choice of 1 of 2 random
200x50x Emblem selections (e.g.200x50x Fighter Emblems OR200x50x Rogue Emblems)
I have flagged this for possible merge / move to General Discussion. Sorry, but this is NOT a bug. Again, I agree with you that the Alchemy Lab would benefit from being adjusted. But the rewards you’re showing are not an error. If you review the thread I linked you’ll find this is generally the consensus and even another person in your situation.