3OSC' FM-modulation. Does that work correct?

System Information

Windows 10

LMMS Version(s)

At least all >= 1.0

Most Recent Working Version

Has never worked

Bug Summary

FM modulation is not 'working' in 3OSC
Output is mostly noise or there is almost no output at all.
Attempting to play a chord results in disharmonics.
We can compare the FM-output of 3OSC with FM-modulation i zasfx. All shapes results in harmonic output (except square), also for chords.
3OSC sounds off in its modulation matrix, especially for FM-modulation, but SYNC is also strange, especially does RESO variate in intensity when FREQ is changed. It should not.

Expected Behaviour

Output should work in the complete modulation matrix, and produce harmonic sound and not noise.

Steps To Reproduce

Try these settings:

Does not sound like an instrument.

Logs

Screenshots / Minimum Reproducible Project

No response

Please search the issue tracker for existing bug reports before submitting your own.

• I have searched all existing issues and confirmed that this is not a duplicate.

Start with the 3OSC modulation matrix and reproduce the attached settings on Windows 10, comparing its FM output with the described z asfx output. Trace FM and SYNC behavior across oscillator shapes and chords; done means harmonic output without excessive noise and stable RESO intensity when FREQ changes.