No suggestions or autocomplete for labels

Summary

A label doesn't autocomplete and there isn't any suggestions for a label beginning with uppercase

Steps to Reproduce

1. Create a new labels custom field and add it to the appropriate screen
2. Create a new issue in a project, entering a value for this new custom field
   • Value must begin with uppercase (eg. Test)
3. Attempt to create a new issue in the project. For the labels custom field:
   • Verify that the previous label exist by highlighting the field and hitting on the down button on the keyboard
     
   • Enter the first few alphabets of the label you already created (eg. Tes)

Expected Results

The previous label of Test will appear as a suggestion

Actual Results

1. No labels are suggested
   
2. When the full label (eg. Test) is entered, there will be a New Label beside it even though it isn't a new label
   

Notes

1. Does not happen in 7.2
2. If you create a label which doesn't begin with uppercase, it behaves normally
   

No known workaround