Describe the bug
Title.

To Reproduce
(You spelt behavior wrong):

Go to your TARDIS's Control Sign.
Hit Player Prefs.
Turn SFX on.
Make sure the Action is set to Save.
Select an Interior SFX sound.
Re-enter your TARDIS.

Screenshots
N/A

Log files
There's no errors related to TARDIS.
latest.log

/tardis version output
Please include an output of your /tardis version.

Airplane is just a fork of Paper with more performance features.

Tried, worked. TARDIS is the issue.

It looks like the SFX preference is not toggling properly in the GUI, it is showing as on even when it is off, try toggling it again...

Have updated the 1.16.5 release - https://github.com/eccentricdevotion/TARDIS/releases/tag/1.16.5
Should be fixed now (was already fixed in 1.17.x releases...)

Ah, thanks.

I'm from New Zealand - we spell behaviour with a 'U' in it, as does everybody in Britain and Australia... :)

Do you have the most up-to-date TARDIS-Resource-Pack installed?
Is allow.sfx: true in the config?

1. Yes. I downloaded it via TARDIS's Jenkins page.
2. Yes.

You should be able to use the Minecraft /playsound command to play the sound in-game to check whether the resource pack sounds are working e.g.:
/playsound tardis:tardis_hum_copper master eccentric_nz