Exchange2016 / ECP: 500 error after login (but only with Office365 users)

Hi Tech Community,

I initially had a hybrid environment with an Exchange 2010 server, an Exchange 2013 and Exchange Online (all mailboxes are on Exchange Online).
Following a bad security patch on Exchange 2013, I was forced to create a new Windows 2016 server and install Exchange 2016 CU19.
The installation was successful and also the connection to Office365, the problem is:
- if I try to access the ECP page with a user created on Exchange 2016 to whom I have given the "Organization Management" role, I have no problem
- if I try to access the same page with a user who has the mailbox on Office365 and who has the "Organization Management" role I get the "HTTP ERROR 500"

Can you help me?
Luciano