Synth Filter Cutoff Automation Help

Is there a way to automate the filter on the synth engines? For example, I want it to open up a low pass filter as it plays through the pattern. I’ve tried using the low-pass (L) filter FX and starting it from 0-100, but it seems like the effect slots don’t work on the synth engines. I’ve also tried assigning the Filter Cutoff in one of the macros and then using the Macro in one of the FX slots and have it go from 65-127 (setting it to anywhere between 0-64 doesnt play anything other than an audible thud), as well as setting the filter on the synth patch to 20Hz. That seems to work a bit, but nowhere close to using the low-pass filter FX on a sample. I am currently trying this using the FAT engine with an init patch. I’ve also tried rendering the synth as a sample and using the filter cutoff automation on that, but what I’m assuming is the envelope sounds different and frankly a bit bad haha. Just wanted to see if there was something that I’m missing.