Modal abilities (e.g. Defender) lose all particle effects if you save and load a game while they are still active. This was reported in earlier versions as well. Additionally, attacking with wildstrike burn/shock/freeze etc. no longer produces elemental particle effects. Burning lash on Durance's staff also doesn't trigger the flame particles.

 

I apologize if this has already been acknowledged.

The elemental particle effects don't appear on weapons that already come with a lash effect (i.e. Hearth Harvest). The effect appears if you enchant a weapon with a lash effect, but it still doesn't produce the elemental effect when hitting enemies.