After my private keys was imported i clearly seen 0.203 btc (1478 eur at the time) until the restart.
Only the "watch-only" wallet has no coin, but the other two wallet has and still have it.
We talking about the ChipMixer now, i used them many times. Highly trusted, i believe they didn't used my keys. After the private keys was imported to my wallet, i deleted the session. When i restarted the Electrum / PC the coins was gone from my wallet.
Still, my last imported keys could be compromised, that's the only thing what i can imagine.

If i seen in my available balance last night, the only way it can be gone if someone else re-used my private-keys?
Thanks in advance
Edit: in my transaction history shows no incoming nor outgoing transaction in the last 24 hours.