for me it looks like your rule still try to access and other DB and not the Dictionary file which should be used.
As the DQ instance in P360 is not working with any other DB lookup connection it looks like there is still a reference in.
the issue it self comes not from PIM it is DQ related so I think you have to review your rule.
The DQ Rule pack comes with some Developer hints and also if you import the Default rules you can use it as simple examples also on how the lookup to Dictionaries looks like.
I checked what you said. I can see that the reference table connection in xml export is currently using below:
<DSORuntimeConfig imx:id="U:EHtfoqlBEemuUL4YT7fTgA" xsi:type="dsoconfig:RelationalDSORuntimeConfig" connectInfo="stringIdentity:INFA_DQ_REFDATA_REP"/>
However, when I look at the predefined DQ rule xml in PIM and check the reference table connection, it uses below:
<DSORuntimeConfig imx:id="U:HnZG8CSLEeWqhXrXoJy8HA" xsi:type="dsoconfig:RelationalDSORuntimeConfig" connectInfo="stringIdentity:Staging" connectionName="Staging"/>
I tried changing the connectInfo from INFA_DQ_REFDATA_REP to Staging but it results in error:
Not sure how can I change the connectInfo details in the import xml file without it giving me an error.
Thanks and regards,