Bosch VP4 hangs on 1 minute on wash cycles, but can drain fine otherwise

I have a Bosch Varioperfect 4 and until yesterday I've had no issues with it.

After a regular cotton wash cycle, the machine hung on 1 minute remaining and just sloshed the laundry and water around the drum with no drainage. This continued for at least 20 minutes.

I turned the machine off and drained through the front-panel hose. I also opened the filter which was full of water but otherwise no physical blockage. I then ran a 15-minute superquick wash cycle which worked fine, and I could see it draining (I can physically see the output outside my house).

I then put on another regular cotton cycle and again it hung on 1 minute remaining for at least 10 minutes and just refused to drain. I turned the machine off, then this time instead of manually draining I just put the machine on a spin & drain cycle - it instantly drained all the water and worked as expected.

I'm not sure how to go about fixing this - there doesn't seem to be a physical problem with the pump or the machine draining, it just refuses to do so at the end of wash cycles.