From a previous post.... a discussion about Editing and difference between the Edit Buffer (Edit/Compare), and the Recall Buffer.

The way editing works is when you recall a Voice, Performance, or a Song/Pattern Mixing Part, it is placed in area where you can play it and immediately start to interact with it.
If you make a bunch of changes
_ you can simply move away to another Program — all your edits will be purged... nothing that you changed will remain.
_ you could press the [EDIT] button (again), it will start to flash indicating you are now in “Compare” mode. The program you are working on immediately returns to exactly how it was when you started (no additional changes can be made while the button flashes, values on screen will return to original setting so that you can A/B what you’re doing by toggling EDIT/COMPARE.

As soon as you make any changes to a program, a small letter “E” will appear in the screen — this means that the current data differs from what is stored. If you move away without Storing, the edits are lost... the program reverts to original stored settings.
When you press [EDIT] while in Edit, the Compare mode is launched (flashes), the small “E” becomes a “C” to denote you are in Compare (no changes are allowed while in Compare).

Say you move completely away from what you were editing... which purges all the changes you’ve made, the Voice will return to its original status. Even though you’ve moved away, and have begun playing and editing another Voice, that last edit you made (wherever you left off) is still in what is called “Recall Buffer”.

Press [JOB]
Press [F2] RECALL
You will be asked to confirm if you want to Recall your last Edit, if you confirm, the previous (purged) Edit will return at the exact position you left off editing.

Edit Buffer - used for A/B type comparisons
Recall Buffer - allows you to return to previous editing that you did not STORE.

You mention a MIXING VOICE, which is dropping into full edit on a Normal Voice assigned to a Part. A Mixing Voice location is reserved for each Normal Voice assigned a MIXING Part. It’s data is actually stored to the Song or Pattern — and unlike other Voices assigned to Parts it is not accessible to any Song or Pattern Mixing setup except the one you create it in. In other words it is not stored to the User Bank, like other Voices... it is stored locally in the Song or Pattern Mixing in which you created it. This means when you load the individual Song or individual Pattern the Mixing Voice loads with the Song or Pattern.

There are different Recall Buffers. One for Voice Mode... if you were editing a Voice and move away before storing, that partially edited sound resides in the Recall Buffer.
If you were editing a Performance and move away before storing, that partially edited sound resides in the Recall Buffer.
If you were editing a Mixing setup and you move away from your Song/Pattern Mixing without Storing... you can recall the entire previously edited but not stored MIXING setup.