Sales Rep field is not available in Mass Update Fields for a transaction

There could be scenario where sales rep field needs to be updated to multiple transactions like Estimate, Sales Order, and Invoice etc.,  When user tries to perform mass update for the sales rep field of transactions, Sales Rep field may be found missing. This is caused by enabling the Team Selling Feature. To disable this feature:

• Go to Setup > Company  > Enable Features
• Click on CRM tab
• Under the Sales Section, uncheck Team Selling and Click on Save