Hello,
I update from 5.5.2 to 5.5.5 (skipped 5.5.4).
I process normally as my usual workflow. Then in the end (after visual deflicker), I should read metadata from LR, but the option is disabled (grey).
So i can't load the metadata and can't go on with the export.
Please any ideas to solve it? Thanks a lot.

Most likely there is an orphaned image (that you deleted in LRT) in Lightroom, then it refuses to read metadata.
Solution: right click on the folder in Lightroom, then *synchronize*.
Now you should be able to read metadata.

Sent mobile...

Oh yes! It was that! Solved! Thanks a lot for the speed of light help!