SVA to catch a signal assertion during ACK phase

Avoid multiple antecedents is a great input! thank you!
Why the $stable(intr)? The opposite of $stable is $changed. Is this what you want?
I’m trying to write this assert for the scenario where the packet is 38 vclk cycles long. intr can assert anytime during these 38 cycles.
The assert should capture only the packets where intr asserts between 20-24 cycles of vclk and clear in the following 3clks.
I want the assert to be inactive for the rest of the packets.

The property I wrote was asserting for all the packets, if I use $stable it asserts only for those packets where intr is not stable. But $stable led to other issues.

The property you gave me works perfectly for the packets where I’m expecting this behavior, however reports error for the rest of the packets. How can I disable the property for the packets where intr is stable? Could you please help.
Thank you again!