SUMMARY
For a variety of reasons, Baloo may fail to index a file's contents. `balooctl6 failed` will show the first 128 of these files. Sometimes the failure was transient or spurious, but entering `balooctl6 index /path/to/failed/file` will not actually reindex the file's contents even though it says it did. You have to clear the file out of Baloo's index first or change the file's modified date; only then baloo will actually reindex the file's contents as you requested.

STEPS TO REPRODUCE
(These assume you're on a Linux system like Fedora that appends "6" to all the baloo command-line tools in KDE Frameworks version 6.)

1. In a terminal, run `balooctl6 failed`.
2. Find some plain text file in that output which Baloo did not index that seems legit, let's call it /path/to/file.txt
3. Run `balooshow6 -x /path/to/file.txt` to confirm that "Plain Text Terms" is empty.
4. Run `balooctl6 index /path/to/file.txt` to tell Baloo to index the file.
5. Run  `balooshow6 -x /path/to/file.txt` to see if Baloo indexed the file contents this time.

OBSERVED RESULT
`balooctl6 index /path/to/file.txt' happily prints
    Indexing /media/Windows/Users/spage/Documents/computer_crap/Fedora_misc/kdesrc-build_woes.txt
    File(s) indexed
(I have baloo debug output enabled)

But there are still no terms in the index from this file's contents! Running `balooctl6 index /path/to/file.txt` on a file that failed to index seemingly does _nothing_. You have to first clear the file from the index with `balooctl6 clear` and then run `balooctl6 index`, or modify the file.

EXPECTED RESULT

No matter what, the command `balooctl6 index` should force Baloo to reindex a file. If it's going to print "Indexing /path/to/file.txt", it needs to actually do the work, or tell the user why it didn't.

In general Baloo commands need better logging.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma:
KDE Plasma Version: 6.3.3
KDE Frameworks Version: 6.12.0
Qt Version: 6.8.2

ADDITIONAL INFORMATION

You can also force Baloo to actually index the contents of these failed files by updating their mtime, e.g. with `touch /path/to/file`.

It would help if `balooctl6 failed` printed why a file failed to index.

balooctl commands such as `balooctl6 show /path/to/file.txt` and `balooctl index` should report if a file is on Baloo's own list of files that it couldn't index. Users shouldn't have to do the work of cross-referencing balooctl subcommands with the output from `balooctl6 failed`.

Baloo commands may need to distinguish indexing the existence of a file at some path and actually indexing the file's contents and metadata. I've checked three text files from `balooctl6 failed` and `balooshow6` knows about the file's existence and its "File Name Terms", even though it doesn't have any Plain Text Terms from their contents.