The document says that you have to use the milking machine, but every time I try to do that she say I already used it that day.
Viewing post in The Princess And The Tower (18+) comments
I think the milking machine has no role in that if I remember correctly. Looked up the walkthrough, no Milking Machine:
Gwynn Demonologist Path (Ending Two) • Once Irith is cured, go to the Institute again • This time, you will observe two girls appearing and entering the Institute • Approach the pedestal and place the spider in there • Regarding the riddle, count the spiders and add seven, but eliminate the first digit (1->8, 9- >(1)6 etc…) • Ask for Gwynn to be enrolled • Ask Gwynn, she refuses • Hide the spider in her bedroom and wait for three nights • Talk to Gwynn again, and she agrees to her demonology training if you bring her a trainee collar • Go to the Institute, ask the Guardian to enter the dungeon and get the training collar • Send Gwynn three times to the Institute for lessons • When she returns from the third time, a cutscene with Nyx will play and the game will move to ending two NOTE: You can follow the ending two path until the second Institute lesson and still achieve the Goblin king ending Congratulations, you have achieved Ending Two
Hmmm, this issue has not been reported before. It might just be a gameplay issue.
I had a quick look into the code. SUB3 is not required for Gwynn to use the milking machine. Once you have built the machine, you can ask Gwynn to "test it out". In that cutscene she will get SUB 3 afterwards. So I assume you did not do that part with Gwynn yet.
If you play the game without mod you can send me a link to your a relevant save game file and I'll have a look.