When Generate/schedule and PDF icon is selected the dashboard pdf's are only a white/blank page on Dashboard Designer.
Release : 20.3 with July Kit - ump_dashboard-20.3.3-HF3
Component : UIM OPERATOR CONSOLE - DASHBOARDS/DESIGNER
This issue was reproduced with ump_dashboard-20.3.3-HF3.
This will addressed/fixed in upcoming August HF.
You can revert to ump_dashboard-20.3.3-HF2 because the pdf download was working fine with data in Hf2.