You may have found a bug in the Assistant.

But try another way:

1) Use the Staff Tool to add a blank staff (this will be for the Bass TAB).

2) Selection Tool. Select the blank staff.

3) Utilities menu > Change Instrument…

Choose

Tablature > 4 string Bass [TAB]

Does that work for you?

It works for me (Finale v27).

Håkan Pettersson,

1) I spoke too soon.

This may not be a bug in the Assistant, but rather a matter of whether the actual Finale document contains a Definition of 4 string Bass.

Before you change the instrument to 4 string Bass [TAB], first make sure that the Finale document contains a defined 4 string Bass:

When you have done so, try the utility Change Instrument, and change the instrument to 4 string Bass [TAB].

2) I have sent you a Finale v26 document.

Do yourself a favor:

Please remove your e-mail @dress before the spam bots find it.