This just happened twice in the same race in career mode (Canada, season 1, 100% race length, 110% difficulty), first from ultrasofts to inters and then the other way around. This seems to happen when pitting both drivers would result in a double stack. Problem is, even on 100% length, the driver staying out always ends up losing a lot of time because the transitioning happens much too quickly once the cutoff point is reached. There's no variance in the time when the AI thinks it's right to pit - as soon as Jeff says it's time for a strategy change, they start pitting, and if two drivers are within 3-5 seconds, the driver behind stays out, which when transitioning from inters to dry tyres can cost them over 15 seconds even on a short track with a fast pit lane (Canada). Vettel just dropped from a secure P4 with a chance of finishing P3 or even P2 to a distant P5, losing over 15 seconds to Raikkonen (whom he was right behind when it was time to pit) on the second stop as a result of him staying out. The exact same thing happened to the exact same driver earlier in the race when doing the opposite transition - in fact, both times, he was so slow that Hamilton ended up hitting him, with Lewis getting warned on the first occasion for it.
There's not much I can illustrate through screencaps as I forgot to take any of Vettel being on the wrong tyre, but I know for sure that both times he was in 2nd when it happened as Raikkonen and Hamilton ahead of him pitted, so I could clearly see that he was still on the wrong compound. I do at least have the finishing gaps and Hamilton's warning. The transition points were lap 45 (Vettel came in at the end of L46 because Raikkonen just ahead came in on L45) and 65 (Vettel came in at the end of L66 because Raikkonen just ahead came in on L65). For the majority of the race, Hamilton was 6s ahead of Raikkonen, with Vettel within a further 2-3s back upon reaching the cutoff points, so the pace loss was so extreme on the wrong tyres that even with just that gap, Hamilton on the right tyres was able to catch and even hit Vettel. This bug seems to extend back to at least F1 2016 and was never fixed there either.