Hi, I investigated this even further. Derby DB version 10.14.2.0 is not having this problem. So in the same environment (LinuxMint 19, Java 17, NetBeans14) problems are at least with Derby DB 10.15.2.0 and 10.16.1.1.
Thus I still unsure where exactly the problem is, is it NetBeans or Derby DB? Any help or hints appreciated. Anyway, as a workaround, I will stick with 10.14.2.0 for now until the issue is resolved. Regards, Orange