Playing the full campaign of WE at expert (Mori), I get the following problem: Sometimes, when I try to build units, they do not appear on the following turn (even though I have enough koku). When I look at the unit training parchment, the unit is shown in the box, but is half greyed out. If I remove it by right clicking, sometimes the next unit appears the following year, sometimes it doesn't. I have to do more testing, but I think this only happens in provinces where I have used retraining.

With Shimazu breathing down my neck, it can be very uncomfortable