This is unlikely to be an LE issue as we're not doing anything more than packaging Tvheadend. It is possible that differences in the two versions are due to changes in Tvheadend itself. It's also possible that the issue resides in the browser.
I'm wondering if this is the same as https://tvheadend.org/d/9323-recordings-dont-play-anymore/8 ?
NB: Although there are quite a few Tvheadend users around here the best place to report and debug Tvheadend problems is normally the Tvheadend forum.