Brush Tool Effect Disappears Randomly

[Jason Burnett]

I have designed a bunch of nice brushes that simulate various types of pipes and cables.

Most recently, I have been working with PVC pipes that have flared ends, so I had to create a new set of brushes that had flared ends.

I got them all working fine and used the Brush Pallet to scale them to 20% and they still looked great.

However, when I tried to make the fifth or so pipe flared on both ends, suddenly all of the newly defined brushes stopped working. As in the paths they were applied to disappeared. And by disappeared, I mean that the stroke shows up, the appearance panel doesn't show any change in opacity, the shape remains, but no stroke. And no brush-stroke either.

MIssing Strokes with some Brushes

This shows the same path with different brushes applied. Notice the bottom three have disappeared.

 This is the default brush at 100px x 100px

This is the default brush duplicated and applied with 20% scaling to preserve the shapes on the ends.

This is the default brush duplicated with modifications made to accommodate the flared head.

I have tried two version of Illustrator (beta, 25) and the same problem. It's not a memory problem because I have tried rebooting and running illustrator with 50% of my available RAM (32Gb) dedicated to it and generous swap disks including two 2 NVMEs and 2 ssds (plenty of cache space). 

The strange thing is that all of the brushes were working great until suddenly they just stopped. Now only the first two work.

And I have even tried copying the brushes into a clean file by copying and pasting paths with the brushes applied and still doesn't work. 

This is the first time I have had this problem in more than 20+ years. Anybody have any idea what could be happening? Thanks for any input.

p.s.
Just to be sure that I wasn't having script or plugin issues, these were taken when I was in Safe Mode. 

[Monika Gause]

Can you share just one of those brushes when it's applied to a path in an AI file? You have to rename the extension to PDF in order to be able to upload it here.

[Jason Burnett]

Here are two of the brushes. The only difference between them is the scaling. The same path is duplicated next to each of the visible strokes, but the corner is curved and the stroke disappears. 

Thanks for your help.

[Monika Gause]

I think there are 2 problems:

your base element is very slim. The automatic corners wor best on square elements. 

You have a weird stacking in your base group. There is an invisible rectangle on top and there is another one in the bottom. There needs to be exactly one: in the bottom.

[Jason Burnett]

Come to find out this only happens so far when using the corner tool or curved path (quadratic or  cubic) It appears that strokes work okay until I use the corner tool or extend the handlebars*, then they disappear. Actually doesn't work whenever there's a curve with handlebars (any curve). 

* I know that handlebars is not an officially used term, but the handles are  visualized with tangent lines that SHOULD be called handlebars. 

[Ares Hovhannesyan]

Not sure but .. try to test with GPU preview on/off.. or may be toggle off/on strokes, corner and effect scaling property?

[Jason Burnett]

Great suggestion, but unfortunately the CPU or GPU preview options don't change the issue. Thanks for suggesting this, though. I thought for sure you nailed. it. 

[Jason Burnett]

I was able to fix the problem by not using Illustrator's suggestion for the corners. Instead I created the corner pieces manually by creating circles that matched the lines for both the top and the bottom curves. Then I had to offset the circles by the gap in the line 10px top and bottom. Then extended the circles with the original line segments horizontal and vertical. 

 Still need to work on the corner's a bit, but when shrunk down they look pretty good. 

If anyone knows why Illustrator brushes suggestions for the corners suddenly hides your artwork, I would love to know. Thanks for the suggestions.

[Ton Frederiks]

There are indeed strange thing happening.

Opening your file in an older version (like 2025) gives a warning, expands the brush strokes and removes the brushes from the panel when opened.

When I drag the brush to the artboard, ungroup it and add the unmodified elements to the Swatches panel as pattern tiles.

Recreate the brush with these pattern tiles. The brush works, see attached PDF. Top old, bottom new.

[Kurt Gold]

I think the main culprit are the clipping paths that are parts of the various brush elements.

Probably the brush will work correctly if you create the brush elements without any clipping path.