Hi,
Thank you for the details!
1. The problem with the date filter, that it only contains the year, not the month and the day. The datepicker UI script gets confused when the data is missing, and it basically resets to the initial value. I changed it back to the default format, that should work all right: https://i.imgur.com/ZVXLcIX.png
2. Well, to search the title or the content you should use the search input instead of a custom field filter. The custom field filters are mean to filter the post custom field metadata. Post titles, contents and excerpts are not custom fields.
For this to work, you should remove the topic filter, and turn the search input back on and select the title and the content for search only.