libreoffice 6.4 date dropdown issue

Hello Friends,
I have upgrade my pc from KUBUNTU 18.04 to 20.04 yesterday. After that my application in Libreoffice Calc is not working correctly. My application has Date drop down control in the form. When I click on Date drop down button it kind of hangs for a while and released after some time. During this hanging time, I can move my mouse and other buttons are clickable but no cursor display. The cursor comes back after a while (may be after few minutes). Again second time I click on the date control, again same thing happening.

Please note, my application is working well with Calc 6.0 and earlier versions.

Current Libreoffice Calc version given below :

Build ID: 1:6.4.3-0ubuntu0.20.04.1
CPU threads: 4; OS: Linux 5.4; UI render: default; VCL: kf5;
Locale: en-IN (en_IN); UI-Language: en-US
Calc: threaded

Can anyone shed some light on this?

Thanks and Regards

a sample document might help to help …