I’m putting this under Linux because I think it relates to that OS rather than OS X, but the phenomenon was observed on my mac. This may be more for your amusement than anything else, but it could speak to some issue or another.
I have a large complex file I’ve been using on my Mac. It has a project note file. I opened the file in Linux (it was not opened on my Mac at the time, and in fact, Scriv. was not running on the Mac at all).
I opened the file, copied a single scene (select all and copy) and closed the file and shut down Scrivener for Linux.
Later when I opened the file on my mac, a list of terms and such in my Project Notes file went from being just plain words to being XML-ish gibberish with the original term in place:
{\rtf1\ansi\ansicpg1252\uc1\deff0
{\fonttbl{\f0\fnil\fcharset1252\fprq2 Sans Serif;}{\f1\fnil\fcharset1252\fprq2 Helvetica;CourierHP;}}
{\colortbl;\red0\green0\blue0;}
\paperw12240\paperh15840\margl1800\margr1800\margt1440\margb1440\fet2\ftnbj\aenddoc
\pgnrestart\pgnstarts0
\pard\plain \tx560\tx1120\tx1680\tx2240\tx2800\tx3360\tx3920\tx4480\tx5040\tx5600\tx6160\tx6720\fi0\ltrch\loch {\f0\fs24\cf1 lethocade}
\par\pard\plain \tx720\tx1440\tx2160\tx2880\tx3600\tx4320\fi360\sl360\slmult1\ltrch\loch {\f1\fs24\cf1 lethocrynes}
\par\plain \f1\fs24\cf1
\par\pard\plain \fi0\ltrch\loch {\f1\fs28\cf1 Gem deva}
\par\plain {\f1\fs28\cf1 Dia deva}
\par\plain {\f1\fs28\cf1 Range deva}
\par\plain {\f1\fs28\cf1 Nalinois}
\par\plain {\f1\fs28\cf1 Vula}
\par\plain {\f1\fs28\cf1 No’estra}
\par\plain {\f1\fs28\cf1 Sotans~}
\par\plain \f1\fs28\cf1
\par\plain \f1\fs28\cf1
\par\pard\plain \tx720\tx1440\tx2160\tx2880\tx3600\tx4320\fi360\sl288\slmult1\ltrch\loch {\f1\fs28\cf1 Nalintown }
\par\plain \f1\fs28\cf1
\par\plain {\f1\fs28\cf1 Ozarka CANT BE OZARKA yes it canbe, ozark alabama! }
\par\plain \f1\fs28\cf1
\par\plain \f1\fs28\cf1
\par\plain \f1\fs28\cf1
\par\pard\plain \tx560\tx1120\tx1680\tx2240\tx2800\tx3360\tx3920\tx4480\tx5040\tx5600\tx6160\tx6720\fi0\ltrch\loch {\f1\fs24\cf1 The Crew = Land and History Working Group}
\par\plain {\f1\fs24\cf1 Mississippi River, Big River = }{\f1\fs26\i1\cf1 Messipi}
\par\plain {\f1\fs26\i1\cf1 St Anthrony Rapids Sanantoni }
\par\plain \f1\fs28\i0\cf1
\par\pard\plain \tx720\tx1440\tx2160\tx2880\tx3600\tx4320\fi360\sl360\slmult1\ltrch\loch {\f1\fs24\i0\cf1 canyonlands}
\par\pard\plain \fi0\ltrch\loch \f1\fs28\i0\cf1
\par\pard\plain \tx0\tx2026\tqr\tx2700\tx3240\tx3740\fi694\sl360\slmult1\ltrch\loch {\f1\fs24\i0\cf1 Landscape History Working Group}
\par\plain \f1\fs24\i0\cf1
\par\pard\plain \tx720\tx1440\tx2160\tx2880\tx3600\tx4320\fi360\sl360\slmult1\ltrch\loch {\f1\fs24\i0\cf1 ganjaweed}
\par\plain \f1\fs24\i0\cf1
\par\pard\plain \tx560\tx1120\tx1680\tx2240\tx2800\tx3360\tx3920\tx4480\tx5040\tx5600\tx6160\tx6720\fi0\ltrch\loch {\f1\fs24\i0\cf1 lethocade}}