Strange Bug in a Performance?

[Midimaster]

Hello and thanks for open the forum to me.

I'm new to Juno-DS-76 and tried to create my very first performances.

Now I have a problem with a performance that randomly sounds different. Some days it works, some days not...

The performance has 5 Sounds:

A "bass" sound, that goes over nearly the whole keyboard C0-B5,

followed by four sample sound:
"BUM" from keys C6-C#6
"CLAP" from D6-D#6
"BUM-BUM-CLAP" at E6 and the last...
"WE WILL ROCK YOU" singing from F6-... upto the end

I saved this as a user performance 005 and stored this to FAVORITE 3
In Favorite 1 I have a single sound E-PIANO-patch only
In Favorite 2 I have a SPLIT made of strings and synthi

When I now press C6 I only hear the "BUM". I change to FAVORITE 1 and the E-PIANO is perfect. Then back to FAVORITE 3 and only the "BUM" is at C6 as I expected it.

But sometime when I call FAVORITE 3. I hear the "BUM" together with the "bass" at C6: Suddenly the Bass goes from C0 upto C7.

The same when I step through the performances with the cursor.... sometime the "BUM" is alone... sometimes it comes together with the bass.

Did anybody already had the same problems and knows the reason or a solution?