The PM stops the washing cycle, there is a little foam inside and powder that has not been washed out of the filling tray. Zanussi ZDV91506FA ⇐ Other manufacturers

[mrPu]

Hello!
Maybe someone has encountered a similar problem or knows where to dig.
I always wash dishes in the "auto" mode. A preliminary estimate of the cycle time of the PM itself is 2 hours 10 minutes.
Sometimes after about an hour of washing, the machine stops the cycle (drains water and opens the door as at the end of the cycle). In this case, the end of the cycle timer always shows 30-31 minutes (at normal completion of the cycle, the timer shows 5 minutes for cooling the dishes). There is a little foam inside at the bottom, a little detergent powder remains in the detergent tray (about 1/4 of the original volume, but sometimes less, sometimes not at all, but there is a persistent smell of powder). I wash the dishes in a short cycle for 30 minutes.
That is, as I understand it, the machine does not reach the rinse cycle. Probably does not complete the main wash cycle if traces of powder remain.
Facts:
1) This does not always happen, in about half of the cases the wash is completed normally;
2) PM water it always heats up, when opening the door prematurely, steam always comes out;
3) All filters and sprinklers inside the PM are always clean, since before washing I always remove food residues from the dishes;
4) I try different detergents, but always special (for PM);
5) PM does not signal any errors;
6) The water in the pipeline is soft (I measure it periodically with testers). In the PM settings I set the level of water hardness (in accordance with the instructions for the PM);
7) I do not use tablets, but separately salt, detergent and rinse aid;
8) the PM is in an alert state (in use after purchase, 2 years with washing dishes 2 times a week):
9) Once every two months I run a short washing cycle with a special product for servicing the PM.

The situation is clouded by the fact that You won’t leave the PM to wash dishes without control in order to track whether the cycle has completed normally or not (you wouldn’t want to get too full of detergent).
Please give advice on identifying the reason for this behavior of the PM.

[mrPu]

The other day there was a development in the situation. During a technical wash without dishes, I scattered a little more cleaning powder than usual. For the first time, error 30 (or i30) occurred. At the same time, the washing stopped, the pump continuously pumped out water, although it was no longer at the bottom.
Removal of the side overlay panels showed that foam had leaked into the pan and the float was activated.
It seems that in quantity detergent lies the answer to my question. Although I always put no more than half of it (according to the mark in the tray). Probably soft water (50 ppm, according to the Chinese tester) allows a small amount of detergent to form a lot of foam. But how does this foam affect the interruption of the auto wash mode without an error signal? The washing always stops in one place (according to the countdown timer, 00:31 minutes remain until the end), there is a small amount of foam inside.
I will experiment with the amount of powder, the next dose is 1/4 of the full tray.
And yet the question of interrupting the cycle without an error signal still remains open...