HW IEC: Printing directory with `DIR` sometimes not completing

[woepaul]

Test Environment (required)

• Platform: MEGA65R3
• ROM Release: V999422
• Core Commit: mega65r3-20260628.11-develo-a6c711c.cor

Listing the directory of my jiffy-dos enabled 1571 disk drive attached as drive 9 does not always work

To Reproduce
Steps to reproduce the behavior:

1. Boot MEGA65 with core above.
2. Ensure ROM V999422 is in use.
3. Use @ U9 to check if 1571 can be seen and is identified as jiffy-dos enabled
4. Run DIR several times until you observe the issue shown in the screenshot.

Switching to different CPU speeds does not change the behavior in any way.
This is reproducible with 1, 2, 3.5 and 40 MHz

Expected behavior
DIR should always work and never stop printing till the end of the listing.
Switching to ROM V920422 makes DIR work 100% reliable.

Screenshots

[woepaul]

Let me know if you need more details of if you want me to test something else on this hardware configuration.