Rest sensor gone when its unable to retrieve data

Ive got a strange issue with a rest sensor that works fine when the inverter is online (so I’m able to see the sensor and incoming data in it), but in de evening when its offline, the sensor is gone in HA (can’t find it on the entities page).
Is this by design? Is there something I can do to make it persistent?
Could a restart of HA possibly be the cause?

‘‘sensor:
platform: rest
scan_interval: 300
resource: !secret solax_local_ip
payload: !secret solax_local_realtime_payload
method: POST
name: “solax_rest_local”
json_attributes:
- SN
- ver’’

Please follow the instructions in the pinned topic:
How to help us help you - or How to ask a good question - Configuration - Home Assistant Community (home-assistant.io)

Specifically, number 11.