Unfortunately the latest update did resolve that issue, but not this. I can post the log I have, versions, etc.
I’m running on a Mac OS X 10.11.3, Mono 4.4.2 and Aspose.Slides for .NET NuGet package 16.1.0
Mono JIT compiler version 4.2.2 (explicit/996df3c Wed Jan 20 00:19:48 EST 2016)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
TLS: normal
SIGSEGV: altstack
Notification: kqueue
Architecture: x86
Disabled: none
Misc: softdebug
LLVM: yes(3.6.0svn-mono-(detached/a173357)
GC: sgen
P.S.: Sometimes I do get this stacktrace:
A null reference or invalid value was found [GDI+ status: InvalidParameter]:
at System.Drawing.GDIPlus.CheckStatus (Status status) [0x0009b] in /private/tmp/source-mono-mac-4.2.0-branch-c6sr1/bockbuild-mono-4.2.0-branch/profiles/mono-mac-xamarin/build-root/mono-4.2.2/mcs/class/System.Drawing/System.Drawing/gdipFunctions.cs:212
at System.Drawing.Bitmap..ctor (Int32 width, Int32 height, PixelFormat format) [0x00017] in /private/tmp/source-mono-mac-4.2.0-branch-c6sr1/bockbuild-mono-4.2.0-branch/profiles/mono-mac-xamarin/build-root/mono-4.2.2/mcs/class/System.Drawing/System.Drawing/Bitmap.cs:95
at System.Drawing.Bitmap..ctor (Int32 width, Int32 height) [0x00000] in /private/tmp/source-mono-mac-4.2.0-branch-c6sr1/bockbuild-mono-4.2.0-branch/profiles/mono-mac-xamarin/build-root/mono-4.2.2/mcs/class/System.Drawing/System.Drawing/Bitmap.cs:76
at (wrapper remoting-invoke-with-check) System.Drawing.Bitmap:.ctor (int,int)
at . ( ) [0x0013d] in :0
at . ( ) [0x00028] in :0
at . ( ) [0x00084] in :0
at . ( ) [0x00000] in :0
at . ( ) [0x00011] in :0
at . ( ) [0x00007] in :0
at . ( ) [0x00011] in :0
at . ( ) [0x00007] in :0
at . ( ) [0x00000] in :0
at . (Aspose.Slides.Presentation , System.IO.Stream , System.Int32[] , Aspose.Slides.Export.PdfOptions) [0x0014d] in :0
at . (Aspose.Slides.Presentation , System.IO.Stream , Aspose.Slides.Export.PdfOptions ) [0x00029] in :0
at Aspose.Slides.Presentation.Save (System.IO.Stream stream, SaveFormat format, ISaveOptions options) [0x000fd] in :0
at Aspose.Slides.Presentation.Save (System.String fname, SaveFormat format, ISaveOptions options) [0x00009] in :0