wisco kid said
Not sure if it just me, but I can't seem to match Violin 4 to the playback. If I am reading/hearing correctly it seems measure 26 is missing?  

For my recording I will simply sustain the tremolo F-natural for another measure.  It seems to work.

Apologies if I am off base here.  

 Oh...

 First - WELCOME @wisco kid 

 May I ask - which playback are you using ?   The "animated" ( videos captured from MuseScore that I posted ) or the "real" click-track posted by Pierre ( @Fiddlerman )

  I'll go and check the ones I did in case that's what you're using - thanks for pointing this out....

  Also - let us know the precise score-sheet you're working from.... ( if you are )

  Thanks for the feedback - we'll check it out  

Holy smoke, as they say....   This is NOT the complete answer - BUT - the .pdf scores were issued quite a bit of time in advance of the actual click / play-along track - and personally - I'm not sure of their origin.

I thought I was going insane for a while - but look at this @Fiddlerman and @wisco kid

Here's the .pdf for vln 4 - it took me AGES to spot this - *MY* pasted bar numbers are in red - 

  On the line that starts at bar 25 ....   there are six bars - 25, 26, 27, 28, 29, 30

  The line starting 32 ( in black, the original in the pdf ) should be 31

  This offset-by-one-bar continues all the way to the end, and the last bar is "apparently" bar 57 - BUT - it's really only the 56th bar in THAT document.  The actual play-along has 57 bars.....

  How this occurred is outwith my control ( I didn't generate these .pdfs ) - BUT - what you say is effectively correct @wisco kid - BECAUSE - the actual play-along track has the "missing bar" present - 

  .... although there are some subtle differences there - bar 25 is shown as a full rest ( not the tremolo F ), bar 26 now makes an appearance - again as a full rest, and the first note (the 2-beat G) in bar 27 appears as a rest as well.

  Very well spotted wisco !    

  I have access to the music-xml files generated by Pierre - and every check I have done suggests that - no - it CONFIRMS that, yes, the play-along is 57 bars long, and (putting to the side the difference between the presence of the trem F or a rest) it is THAT document ( the pdf you refer to ) that is somehow incorrect.    

  Your choice I would say - play it as two bars of F, or silence, it'll be fine.  Same applies to the apparent "missing" G in bar 27 (in the play-along score) - play it or rest it - it won't matter.

  I'll bring this to Pierre's attention, and in the meantime, I am now driven to go check the other original pdf files....   (unless you have worked through them yourself, wisco and found them OK ?   )

EDIT : I have since checked all the original .pdf files.  The only one that exhibits this problem is vln 4.   The rest are fine !

wisco kid said
.....   All the best of the season to you and yours, and I look forward to viewing the finished product.

  And the same back at you !   May it be a good one !