Cascade Hops: Indoor in pot, spider mite infestation, baby side shoots dying off :-/

Hallo all!
I've been using this forum for some time for valuable information, and have decided to join.
This is the first year I decided to grow my own hops, and so far it's been fantastic. I got a Cascade rhizome and planted it into a 50 liter pot with a trellis, and the growth season was explosive. Hard to measure, but the main vine got to about 15 meters long, and it's still growing. But now it is late in the season, and I'm worried I won't get any cones at all. I had a massive spider mite infestation covering the whole plant, and I've used specialized insecticide, and it appears to have worked, but the damage has been done. I've used fertilizer and specialized potassium fertilizer as well, and while vine growth has been huge, many (if not now most) of the little side shoots are dying and falling off. This has been happening throughout the season, but now it's even happening on the young side shoots only 2 or 3 weeks old. Why is this happening? It seems like the plant is choosing to selectively let them die off while still growing the vines like mad. In many of the places where the side shoots have fallen off, new ones have begun to grow, but rather slowly.

I grow my hops in a "Wintergarten" which is glass enclosed, and I live in northern Germany, so the summer days are very long and most of the plant gets direct sunlight. Already being near September, I'm wondering if I'll get no cones at all. I got my coworker a rhizome as well (Mt. Hood), and he planted his outside, never really cared for it or did anything, and his cones are now ready for harvest.

I attached two images, one of the side shoots dying, and one of the whole plant.

Danke schön for your help guys!

What is the humidity in the growing area? It is hard to see from the pictures, but if the dead side shoots are covered with fuzz it is probably a Botrytis sp. (Grey Mould). It can be tricky to determine which came first though, the dead shoots, or the botrytis, since Grey Mould is an extremely common fungus that usually just infects dead tissue (saporophyte).

If the humidity is not higher than 85 %RH or so, then I am out of ideas. Since the plant is growing so well overall, I would make a second guess of water stress.

I keep the windows open, so the humidity is relatively low, definitely not above 85% or the windows will fog up. The dead side shoots don't seem to have any fuzz on them at all, just brown and dried out. Also the presence of spider mites shows that the humidity is probably actually too low.

Would water stress be not enough water or too much? I typically give the 50 liter pot about 500 ml of water every other day or sometimes daily if it's very hot (the water can evaporate out super quickly).