Yes!! This was the solution. Thx very much!
I had no idea before that a user restriction could be the cause.
(Saves me tons of work trying to rescue history data from old setup to new setup with a databasetool, if even/ever possible with SQLLite.)

Regards,
M. Esser

SETUP
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Domoticz 2024.7 on RPI3
8 years Gas/El history
4 years temperature history

PROBLEM
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Now experiencing added temperature sensors only have a current data value but do not log even when set to used in the device setup.
Sensors can be replace with new index after batteries have ...