Repro

1. Issue can be replicated in custom application.
2. Create a look up field of customer data type in case main form.
3. Once the look up is created for eg Billing account field is look up.
4. Click on column options=> Add column => related.
5. We can see Billing account (Account) and Billing account (Contacts) as it is customer data type. 
6. If we select Address 1 zip code, city, county, country, Address 1 zip code etc. from Billing account (Account).
7. The same attributes cannot be seen in Billing account (Contacts), however, it can be seen in Billing account (Account) again after we perform same steps from step 4.
8. If we select same attributes from Billing account (Contacts) first, then there is no issue, we can see same attributes even in Billing account (Account).
9. We need to check if anyone wants to raise this to Product team and get it fixed, as they say it is by design behavior.

Any comments will be appreciated!