"Project cannot be built until its prerequisite is built" errors each time I close & open VSCode

I have a multi-module Maven project that I created using Eclipse, and now I am trying to migrate to VSCode.

I have opened the project in VSCode, and it has updated all .project and .classpath files. There is no error in the project, and everything seems to work perfectly.
But after I close VSCode and open it again, without having changed a single line, after Java builds everything, suddenly most of the modules are in red, and I see this type of error in the Problems tab:

"The project cannot be built until its prerequisite XXX is built. Cleaning and building all projects is recommended"

If I "Clean Java Language Server Workspace", the problems disappear, until I close+open VSCode again.
If I "Force Java Compilation > Full", the same. Problems disappear until the next restart.

I guess this shouldn't happen, but I don't know if it is a problem in my project (as I've said, everything works until I close the workspace), I have something configured incorrectly or it is a bug in vscode-java (and if so, if there's any workaround).

I am using JDK 8.

I have tried the pre-release version too, but I get the same problems.

Thank you in advance, please let me know if you need more info.

Start by reproducing the failure with the multi-module Maven project after reopening VSCode, comparing the .project and .classpath files before and after Java builds. Check whether cleaning the Java Language Server Workspace or using Force Java Compilation > Full changes the result. Done means identifying the restart-related cause or a reliable workaround for the prerequisite errors.