Benjamin... I'm stoked that you solved the issue (link to original question (https://developer.salesforce.com/forums/?id=9062I000000g6j6QAA#!/feedtype=SINGLE_QUESTION_SEARCH_RESULT&id=9062I000000g6j6QAA)) but...I'm a little lost on the solution steps.
1.) I'm not that familiar with workbench 
2.) I'm vaguely familiar with VLOOKUP functionality...
I have a picklist field that I want to convert to a Lookup to make data entry easier for end users to enter the data and easier to maintain.

I created a "similar" lookup field to replace the picklist field (so that moving forward, end users can enter the data there).
to deal with existing records and move the data from the existing picklist value field to the lookup value (they are an exact match), I'm lost on your process.

Is there a way that you could guide me to get those steps?
Thanks,
Dominic
Here are my Objects and Field Names:
Parent Object: Case
Lookup Object: Purchase Locations

Case Object currently has a Picklist field that has grown too large:
Purchase Location

I want to change the picklist field to a Lookup Field.
Just converting the field type is NOT Possible.
 

Hi, 
I would like to know how long it take for thid pop to stay in salesforce once the EAC configuration is enabled?Its been 2 hours now and I am still seeing the below pop up.Also the user having it setted up does not have many contacts or emails associated with it, so i barely think that is causing the wait time to be longer.
"We are getting Einstein Activity Capture ready for you. While you wait, choose who you want to share emails and events with.Update Sharing Settings"

I have a standard object, "Account", with a custom pick list, "Number", that contains 5 vaules: First, Second, Third, Fourth, and Fifth.

I also have a custom object, "Number", that has 5 records: First, Second, Third, Fourth, and Fifth.

I want to change the pick list "Number" field to be a lookup relationship field that relates to the "Number" custom object.

The only way that I know for certain I could do this is to:
1. Create a new custom field on the "Account" object named "NumberTemporary"
2. Run a script that populates "NumberTemporary" with the current "Number" value
3. Change the "Number" pick list field from a pick list to a lookup relationship
4. Run a script that populates "Number" with the id of the record that corresponds to the "NumberTemporary" value
5. Delete the "NumberTemporary" field

This solution comes with the limitation of only being able to update 10,000 records at a time, and just seems like a dirty way to get it done. I will do this if need be, but I was wondering if there is any better approach.

Thank you!