Price Level > Null Price level sticks with the amount of the Base Price when you select it in a quote, sales order, invoice and cash sale transaction.

Symptoms/Details of Business Requirements/Any Additional Information:
1. Create a new inventory item.
     -- Pricing tab: USD Base Price = $400
     -- Pricing tab: GBP Alternate Price 1 = $300
     -- Save
2. Enter a sales order, quote, invoice or a cash sale transaction.
     -- Select a US Customer.
     -- select the item from Step #1
     -- Change the Price Level from Base Price to Alternate Price 1.

3. Actual Result: Rate is $400 when the expected result should be null.
 

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Solution/Workaround/Gotcha/Recommendation Details:

As a workaround, add the item first by clicking on Add, then go back to the Price Level Dropdown of the first line item, notice that the price level that shows up are the ones that have prices for the currency of the customer. This was filed as a defect. Please see Issue 169378.
 
As a recommendation, a good resolution to this defect is to only show price levels that has prices plus "custom" price level in the currency for the customer that was entered in any of the transactions mentioned above. This way, they will not be selecting a price level that is null for the currency.