Reindex drops timestamp

[Andrii]

I'm trying to reindex data from one index to another.
the query is:
POST _reindex
{
"source": {"index": "log-plt-2020.01.26" },
"dest": { "index": "log-plt-2020.01.26-1" }
}
I see that all dockuments got copied:
GET _cat/indices?v&index=log-plt-2020.01.26
health status index uuid pri rep docs.count docs.deleted store.size pri.store.size
green open log-plt-2020.01.26 8R2iBv3qSW-ybSAau25pZg 3 1 16731072 0 6.5gb 3.2gb
green open log-plt-2020.01.26-1 wYKJgLK1R3eMpfGLtFlRkA 3 1 16731072 0 6.7gb 3.3gb

But when I created a new index pattern for log-plt-2020.01.26-1 Kibana didn't show anything. Then I recreated the index pattern and specify that "I don't want to use the Time Filter". After that, I was able to see all data in the new index. But all events were without @timestamp field. Am I did something wrong?

[spinscale (Alexander Reelsen)]

Can you check the mapping for the @timestamp field in your new index? What does it look like?

[Andrii]

Here is a snippet of my mapping for this index:
"properties": {

      "@timestamp": { "type": "date" },           

      "message": { "type": "text" },

      "stacktrace": { "type": "text" },