Environment: Productivity Suite 4.7.2(4), P1-540 firmware (P1-All_In_One_20260611) . Also reproduced in the simulator. The UDIs are called from Structured Text tasks.

All my PACK BITS and UNPACK BITS instructions inside UDIs stopped updating their output, across more than one UDI. Each of them sits on an always-enabled rung, and a MATH on the next rung uses its output.

In the UDI monitor, the PACK BITS input Value column showed 0 for every bit, even though the same tags showed 1 on adjacent rungs in the same frame. The output stayed at 0. The MATH on the next rung was still executing.Consistent across every UDI in my project that used either of those instructions.

My fix was just to cut and paste the exact same instruction in the same place and do a runtime transfer for every UDI. The project compiled with no errors throughout this whole process and the project looked exactly the same before and after the fix. An earlier version of my project did not have this issue, but there was no changes to the UDI's logic between project versions, only task changes.

I have not been able to replicate this issue.

Additional context, I had multiple 4.7.2 projects open and a 4.4.1 project open on my computer at the same time over a number of days.