Inconsistent results when using Advanced Filter to remove duplicates from cell range (occassionally allowing text duplicates)

LO 6 OS Mojave

I’m using Advanced Filter to assess a cell range, remove duplicates from it, then display the results in another cell range.
However sometimes I find that text duplicates are not omitted from the resultant cell range, only numeric ones, and other times all duplicates are omitted. I can’t seem to work out why this is happening, it seems to occur randomly sometimes.
Each time I am using the same procedure to remove the duplicates, so don’t see why this should happen other than perhaps some sort of bug…
Is this a known bug, or something else? Any workaround? Does the latest release of LO still have this issue?

Thanks.

Please edit your question and attach a (redacted) sample file and describe an example filter where that happens.

Which LO version btw? 6 is just a number that ranges from 6.0.0 to 6.4.6

I’ve had a similar experience too and it’s frustrating.

you are aware that the first row is interpreted as column header, and thus duplicates to that may occur in the data section?