Data variables button

Hi,

since a few days I can´t push the button with the three points from "Data Variables" in the net and the tasks. If I push them, nothing happens and the YAWL Editor freezes. The other buttons and dropdown menus work fine. I have the problem with two computers and a new installation didn´t help.

I have the following system:

YAWL Version 4.2 (build 760)
jdk-12.0.1
jre1.8.0_201
apache-tomcat-7.0.65
Windows 10 Version 1803 (Build 17134.829)

Thanks for help,

Nils

YAWL engine (3.0) not competng start in W7

Hi folks! I am a new user of YAWL, and have come across my first hiccup :(. After the installation (W7, 64 bits) I tru to start the engine, but the button "Engine is starting" simply stays for ages (apparently bringing it up).
I wonder whether there is a way to debug what is happening. Are there any quick hints, known issues... that I can try? IS there a check list I could go through?

Thanks in advance!