Never got OH3.0.0 release version to work with Influx.
It could write and update 1.7.8, but restore didn’t work.
Updated to Influxdb v2.0 and entered openhab/openhab for org/bucket.
After that OH3.0.0-1 always complained about the wrong version “V2” and nothing worked.
Updated OH3.0 to snapshot #2158.
My original v1.7.8 openhab_db database got updated to a bucket named openhab_db/autogen.
It took me a while to grasp the new Organization/bucket concept, but I was able to tune the setting using the info in the doc: InfluxDB (0.9 and newer) - Persistence Services | openHAB
My influxdb.cfg now looks like: (my influxdb user is openhab)
# The name of the database user, e.g. openhab.
# Defaults to: openhab
# The password of the database user.
password=*xxxx*
# The name of the database, e.g. openhab.
# Defaults to: openhab, in V2 this is the organization
db=openhab
# In V2 this is the bucket name:
retentionPolicy=openhab_db/autogen
version=V2