When the number of items in the To Do List is too high (2), no Actions are shown at all (1).
The following message can be found in the BGMD log:
LM 07 Oct 08:56:01,891 [CltHndr_172.17.8.83_Pilot-rosana.onoda_13] ERROR TD_TDB - Problem fetching TodoParameters
>>> com.microsoft.sqlserver.jdbc.SQLServerException: The incoming request has too many parameters. The server supports a maximum of 2100 parameters. Reduce the number of parameters and resend the request.
Problem is solved in Automation Engine 18.1.1.
Filter the actions to show a number that is below 2100 (and clean up).