"Manage Categories" window in a split transaction only opens for the first 2 split rows

[Gigific]

MMEX version:

• 1.5.17
• 1.5.18

Operating System:

• Windows
• Mac OSX
• Linux

Description of the bug

When adding a transaction, if the "Category" field is empty, it is possible to hit "Enter" to open the "Organize Categories" window and select the transaction category.
If the procedure is done for a split transaction, from the 3rd row onwards, the "Organize Categories" window is no longer available when pressing "Enter".

Reproduction

1. Create a new transaction (i.e. in a Checking account)
2. Click the "+" icon to use split categories
3. in the first "Category" field, hit Enter while the field is still empty and observe that a "Manage Categories" window is oped and allows the selection of the category for this part of the split transaction
4. write an amount for the first row in the "Amount" field
5. Click "Add Split" and repeat steps 3-4 for the 2nd row and observe the same behavior:
   
6. BUG: Now a third row is available, but if you hit "Enter" in the empty "Category" field, the "Manage Categories" window does not appear anymore:
   

Is the bug reproducible?

• Always
• Randomly
• Happened only once

Expected result:
The "Manage Categories" window should be available for all the rows of a split transaction when the user hits enter and the field is empty.

Actual result:
The "Manage Categories" window only appears for the first 2 rows.