Just that really. I used a simple 50% wholemeal / 50% white flour recipe that I've used many times without problems.
I gave it 6 hours to rise and it did so by no more than 30%
The wholemeal flour was given to me (shops are out) and after baking I noticed that it's BBD was in 2017. It was a bit lumpy and musty when I poured it out of the packet.
The only other culprits I can think of are the yeast (I baked last week with different flour but the rise was sluggish) and temperature (18 degrees in my house, 15 this morning, but I put the dough on top of the hot water cylinder with a couple of hot water bottles).
The bread tastes slightly sour.
Any advice?