user19382: I have a sequence with various clips, one came from a multi-cam and the other one straight from a video. I had no problem applying the filter to the multicam one:

But when I try to apply it to the other one, it won't let me:

Any ideas why?

user14504: Check to see if the filter is restricted to specific audio file / stream / track types. 
For instance, I believe you’ll get the same issue if you tried to drop filters that apply only to Stereo Tracks to a Mono File Track, such as Swap Channels, Fill Left, Fill Right, etc. Because its impossible to swap left and right channels when youre on a mono track. 
You dont specify what filter, but thats my guess. 
Same goes with Video Filters... there are some filters you cant drop onto video tracks with Alpha, or vice versa. 

19382: <p>I have a sequence with various clips, one came from a multi-cam and the other one straight from a video. I had no problem applying the filter to the multicam one:</p>

<p><a href="https://i.stack.imgur.com/Lzyiq.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Lzyiq.jpg" alt="enter image description here"></a></p>

<p>But when I try to apply it to the other one, it won't let me:</p>

<p><a href="https://i.stack.imgur.com/29JB7.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/29JB7.jpg" alt="enter image description here"></a></p>

<p>Any ideas why?</p>
 14504: <p>Check to see if the filter is restricted to specific audio file / stream / track types. </p>

<p>For instance, I believe you’ll get the same issue if you tried to drop filters that apply only to Stereo Tracks to a Mono File Track, such as Swap Channels, Fill Left, Fill Right, etc. Because its impossible to swap left and right channels when youre on a mono track. </p>

<p>You dont specify what filter, but thats my guess. </p>

<p>Same goes with Video Filters... there are some filters you cant drop onto video tracks with Alpha, or vice versa. </p>
