Welcome to the forum @0x391F
Using a combination of exclude and include filters, intention gets unclear.
Since it’s not in a filter to include or exclude, Duplicati will include. It’s safer.
If you use only include filters, Duplicati is willing enough to exclude the rest.
The current documentation doesn’t detail this, but the old manual describes:
Per default, all files and folders will be backed up. That means, if no rule matches, the file or folder will be included. In the special case that all rules are include rules (which does not make sense when all files and folders are included per default) Duplicati assumes that all other files and folders are meant to be excluded (this had to be defined as another rule in Duplicati 1.3 but most people found that confusing so we changed that in Duplicati 2.0).
There is also a forum Article (rather hard to find) suggesting how to solve this:
Include some files, exclude others. …
To make the including rule effective an additional rule is required that excludes all files that do not match any of the current rules. The filter must say “exclude this, exclude that, include this but nothing else”. The best rule for “but nothing else” is a regular expression that excludes all files. It is-[.*[^/]]on Linux or Mac, and on Windows the rule is-[.*[^\\]]. The rule says “exclude everything that is not a folder”.
A useful filter test tool that is also not mentioned in the new filters manual:
Ignoring gaps, there is a lot in the filters docs that would be worth reading.