It's already a trip halfway around the world at something like 30 km/h. If you're transporting goods that are that sensitive, you're likely doing it by air already. Ships get delayed all the time for various reasons.
This sounds slow at first, but, since you can drive pretty much 24/7, that's still 720km per day. If you're literally going halfway around the world (20.000km), you'll be there in 28 days. Since you drive on water, you'll do few small detours (I assume), so you can actually get those 700km a day.
EU<->China even appears to be "only" 7000 km [0], so if you could drive in a straight line you could get there in 10 days. 14 with usual delays and detours, maybe. That's a reasonable time span for a lot of perishable goods. With the blockage doubling that time, I can easily see how this would affect quite a few goods.
[0] https://www.distancefromto.net/distance-from/Europe/to/China
Also crew change is likely because of on-going investigations, and that will be tricky with the on-going mariner crunch. There's not a lot who are qualified to run a ULCV, especially one straight out of an accident.
Over time as the political situation cleared up a bit most of the crew members were repatriated with just a periodically rotated skeleton crew watching over the ships staying behind.