DLP Policy tip not showing on Outlook 2019 with custom SITs only

I have our users observed DLP policy tip missing for ONLY custom sensitivity types on windows 10 with Outlook 2019 (1808 build) where user has O365 hosted mailbox with correct DLP license. policy tip working fine for in-built (MS) SITs like credit card, ip address etc.

mso20win32client.dll version is : 16.0.10382.20010 @ 

C:\Program Files\Microsoft Office\root\vfs\ProgramFilesCommonX86\Microsoft Shared\OFFICE16

Other side, DLP policy tip working fine (except some - as usual) for both in-build (MS) and custom sensitivity types (SITs) ON device with Windows 10 + Office 365 (2201 - monthly enterprise channel).