When is planned to be released the PowerServer update that will be compatible with the Android API 28? Last time I checked, the tentative release date was in August 31, but now I'm not sure about the new release date.
This issue & a few others are expected to be addressed in the up coming PS2019 MR. The Appeon team is Q/A'ing the MR as we speak. Since it's the Labour Day holiday today, I do not have an update on their testing at this time. However, I suspect that the MR will be released very soon (pending any glaring regression bugs).
Good news, the latest PowerServer Toolkit 2019 EBF- 11.0.2151 which support APL LEVEL 28 has been released and can be downloaded from the Mirror Site now! http://support.appeon.com/index.php?/News/NewsItem/View/142/new-mr-version---appeon-powerbuilder-2019-build-2151-has-been-officially-released
You can also upgrade PowerServer 2019 GA to EBF 2151. http://support.appeon.com/index.php?/News/NewsItem/View/144/new-mr-version-build-2151-for-appeon-powerserver-2019-for-windowsunixlinux-has-been-officially-released