Local Web Preview + Java HTTP Preview = nhttp.exe crash

When I use Local Web Preview, it works fine.

However, if I turn on Java HTTP Preview (File → Tools → Java Debugging Preferences → HTTP Preview ON; Port: 8703)

and try to preview a form (i.e. launch Local Web Preview process), nhttp.exe crashes, and the following prompt appears:

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Caption: Microsoft Visual C++ Runtime Library

Runtime error!

Program: c:\lotus\notes\nhttp.exe

This application has requested the Runtime to terminate it in an unusual way. Please contact the application’s support team for more information.

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BUT, if I turn on Java HTTP Preview, and run nhttp.exe via command line, it works fine, and I am able to debug Java Web agents (I use Domiclipse for that).

Any clues why nhttp.exe crashes when started from Domino Designer?