Slack watched messages in private channel appear as "invalid object" at "invalid date"

Hi,
I set up a private channel in Slack and have make watch if there are new messages, mostly audio notes.

When I run the scenario and I manually choose from the messages in that channel, there only appears “invalid object” at “invalid date”, which makes the selection process impossible if there are more than 2 or 3 messages.

How can I fix this so that the correct date and object type are displayed?

Thanks in advance!