this behavior seems depend on the minor java version pointed to run WebRatio. I don't know which version of java you are using but as you know WebRatio 8 Mobile is compatible only with Java 8 (refer to the "System Requirement" of the Release Notes https://my.webratio.com/learn/learningobject/webratio-mobile-platform-810-release-notes-v-80).
In this case to correctly run WebRatio 8 Mobile I suggest you to install and point to a less recent version of Oracle Java 8. For example 1.8.0_151.
Anyway this does not force you to uninstall your current version of jdk v 1.8 in fact you can manually set the JAVA_HOME environment variable in the WebRatio ini file.
To specify the installed java path to run WebRatio you have to edit the WebRatio.ini file and insert this instruction before -vmargs row:
where "xyz" corresponds to the minor version (e.g. 151)
Moreover if needed, you can also refer to the answer reported here https://my.webratio.com/forum/question-details/web-ratio-mobile-plateform-macos-sierra.