NaN in a project file from this comment in PR #3313 submitted by @Umcaruje
Edit: I edited down the original song to a minimal project.
issue3685.mmp.zip

The project goes silent just as the BitInvader sounds for the first time in bar 5.
<lmms-project version="1.0" creator="LMMS" creatorversion="1.0.0" type="song">
It was created with lmms 1.0.0 and the project breaks in lmms-1.0.91

If you turn the volume knob on the BitInvader track or if you render the project before you hit play the bug isn't triggered. I've been trying to spot something like an undefined variable in there but have come up with nothing so far.

The bug was introduced in 23433a7

23433a70b577bc67f2836c0ae98a4dc48ae40f93 is the first bad commit
commit 23433a70b577bc67f2836c0ae98a4dc48ae40f93
Author: Vesa <contact.diizy@nbl.fi>
Date:   Mon Jun 30 01:59:18 2014 +0300

    Sample-exact models: improve
    - Remove the redundant hasSampleExactData() function. Instead, signal lack of s.ex.data by returning a NULL in valueBuffer()
    - Cache s.ex.buffers and only update them once per period
    - Make valueBuffer() in AutomatableModel threadsafe so that it can be used for NPH's sharing the same model
    - Add sample-exactness to instrumenttrack's vol & pan knobs