When I look at long fields in my columns in Mp3Tag, I see a "..." at the end of the field, but when I click on the field the rest of the tag will appear. So, the information is there, but it seems as if Mp3Tag has a limit on the amount of characters it will display in the column for that field. It seems odd that would be the case.
Please let me know if you think you know what is going on.
On a side note, I have searched and I am wondering if there is a limit to the amount of characters in a field. I seem to remember that m4a uses atoms that are limited to 255 characters to store its tags, but I am not sure if that is the case across all platforms and formats.
This is a very common phenomenon in software development which helps adapt to display limitations and limit side-to-side scrolling. Field width and data width are two different things. Enough of the field of data is displayed to provide a hint while allowing more columns to show, and making it possible to see the complete field contents if you want to, often by simply hovering over the field or clicking and moving the cursor through the data.
There are several bad things about trying to force too much into into a field. And especially there are bad things about using what are called 'special characters' if you ever want to export your data to other software (slash, backslash, single quote, double quote, etc). Software such as database systems use various 'character sets' which assign functionality to charters for formatting purposes. A simple example is the CSV (comma separated values) format often used for moving data between applications. Data that contains commas can drive you insane with formatting efforts.