For some reason the workflow does not let me deflicker.
Very, very annoying.
I cleared all metadata, resetted metadata, deleted .lrt directory, even deleted the Lightroom directory in windows Pictures files.
after auto transition no deflicker.
What also strange is when you start from scratch, the keyframes are still in the memory?

How is this possible when I deleted all information?
Where does the SW stores it history?

it cost me many hours and still no result.

Very frustrating.

First of all, if you work with DNG files or JPGs, then Lightroom will save XMP inside the files itselves, which LRTimelapse cannot remove. Normally this isn't an issue because LRTimelapse will always work with sidecar XMP file, and Lightroom will also use those if they are newer. But if you brute force delete the XMP sidecars, the resigual internal XMP data might appear.
Therefore you should always use "Metadata / Initialize" when you plan to reset a sequence. This will create a fresh, clean set of XMP data to start with.
The avalability of the visual deflicker depends on the visual previews. You need to have all Visual Previews created, before Visual Deflicker gets available. If there is one or more corrupt images where the visual preview creation fail, you need to remove them first before deflicker will work.

In any case, if you experience any further problems, sending over the log file (info menu) will help me to help you without having to do so much guesswork...