Tasks: Reminder removed after synchronization

I am using eM Client as my email client on my desktop. When I create a task with a reminder in eM Client and synchronize it with my mailbox.org account, the reminder date and time are removed.

I contacted eM Client to report this issue, and after investigating, they concluded that the mailbox.org server modifies the task and deletes the reminder.

Could you please look into this and let me know if it can be resolved?