Custom brush stokes end up outlined

i made custom brush string of xs indicate closed road. it's been working fine i'm noticing lot of old files have stroke outlined when open them again. seems correspond brush no longer being in brushes palette: if brush isn't there, xs outlined. i'm not deleting brush deliberately.

 

my process appears same: copy path out of old file , new 1 (which adds brush), there i'm (intermittently) doing wrong causing disappear in files?

this happens when either file corrupt or open in older version has been created.

 

are these files on server?

can upload 1 of these files somewhere , post link here?

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