I am surprised as well to see these issue, as I figure I wouldn't be the only one if this were genuine memory leaks. I can only assume something went wrong during my setup of the SDK.
I have started afresh and have extracted the R21 SDK on my D drive at
There a subfolder named "frameworks" has been created with the content of the SDK.zip
Also inside D:\Projects\Dev\SDK_R21 I have a "plugins" folder, which only contains the extracted "cinema4dsdk" folder (I removed maxonsdk.module and microsdk), and a "project" folder, which contains the solution projectdefinition.txt as follows
Platform=Win64;OSX Type=Solution Solution=\ plugins/cinema4dsdk
I downloaded the projecttool (20190903) and extracted this into
D:\Projects\Dev\SDK_R21, which created a "cinema4d_r21_project_tool_20190903" folder.
In D:\Projects\Dev\SDK_R21 I created a bat file to execute the projecttool, as follows:
I execute this batch file, which generates the plugins solution, which I double click, opening Visual Studio 2017.
I make cinema4dsdk the startup project, enter the Cinema4D executable into the project's debugging properties. Build all (debug, 64bit), start debugging, wait for Cinema 4D to launch, close cinema ... and get the list of memory leaks and dangling references.
As I didn't add a specific plugin folder to the build project, nor did I manually install any plugin, I can confirm there are no plugins available in the Extension menu of Cinema4D.
Windows 10, 64 bit, Professional Edition (build 18362)
4(8)x Intel Core i5-8259U CPU, CPU speed 2310.000
Visual Studio Express 2017 for Windows Desktop Version 15.9.15
Microsoft .NET Framework 4.8.03752