Somehow the input timestamp has a comma instead of a dot. Also Episode Review is showing "Invalid date" for the initial date.
I traced down the first search and it was itsi_event_grouping using the itsi_event_management_group_index_with_close_events macro. This macro brings the itsi_first_event_time variable, which has the incorrect timestamp, including a comma instead of a dot: 1588515619,432.
As a quick fix for the macro I appended a function that replaces comma to a dot, but it hasn't changed the Episode Review dashboard 'invalid date' message.
In the spanish number format comma is used for decimals instead of a dot, it might be related somehow, because i'm using those locales in linux.