Hi Thomas,
I can reproduce it. I know for sure that it worked, because I tested it some years ago but now it fails, but I have no idea since when.
To reproduce the issue I have 2 Groovy files appended. You may have to adapt the jdbc-url to your situation. I used an pretty old groovy version (1.8.9) but it should run with recent versions too.
The real application where it happens uses Java 8 and 9 on Linux/Mac/Windows and I can reproduce it on all 3 OS.
First start StartDB which creates the DB, fills some records in a table and waits for 10 seconds.
A few seconds later start SecondDB which makes a select, which succeeds waits some seconds, so the first process is stopped and gets an 90067-200 on the 2nd select.
I tested it on Linux with h2 1.3.175(6?) and 1.4.200 but the issue occurs on all 3 major OS I use.
Thanks in advance for your help and the excellent work you've done all the years!