Hi, Welcome to the Forum spanky cat!
Here are all important links:
http://lmms.io/forum/viewtopic.php?f=1&t=4740
-A few rules and useful forum instructions
If i understand you correctly, you have an effect made with dual-filter, but in the exported song, you cant hear that effect?Dual Filter is missing after the track's been synced
Is that correct?
Also, please post your:
* OS (+service-pack-version)
* lmms version
* lmms instrument involved
* lmms preset (if a factory preset is used)