Such an interest from people who wants us to provide them with detailed information and then..... Nothing...

It looks like more and more people lose interest in this piece of software... Shame...

You provided no relevant information to reproduce this issue.

Things that are missing are:

• Relevant world (or parts of the world) before the modification through MCA Selector.
• The process of how the chunks have been deleted.
  • Were they deleted using the CLI? Add the command and associated files.
  • Were they deleted using a manual selection? Save the selection as a .csv file and upload it here.
  • Were they deleted using a filter? Add a screenshot of it, the filter query string or the Groovy script to this issue.
• Relevant world (or parts of the world) after the modification through MCA Selector.

In order to reproduce an issue, you need to start from scratch, with no context. Reporting a bug means writing precise instructions that can be followed to the dot without having to resort to guesswork.

I added the piece of the world that is in the issue here. But I see the manner of questions you want to know is beyond me. I used MCA, the program, graphical not cli. In that program there is one (1) way to delete selected chunks (CTRL+D). I used that, for convenience, obviously.
FYI, the server was turned off to modify this, but the real issue here is that next to the selected chunks and blocks when zoomed in, there were also blocks deleted that were not selected. Maybe first try to check that.
And about the way you want us to deliver you everything on a silver platter, is way too much. Because we are modifying this world almost daily, we can't always give the data you need, sometimes you have to do with what you get.

But never mind, I managed to rebuild the affected area, and obviously, I leave MCA selector alone, because I can't trust it does its job as I expect.

Thanks for taking the time to react.