R6 + Core with IEC-Controller + SD2IEC: Transmitted data seems to be corrupted.

[eilers]

Test Environment (required)

• Platform: MEGA65R6
• Core Commit: 6d764c4
• ROM Release: Not yet released. See following to get the ROM: https://wiki.eilers-online.net/IEC-Core-Test

Describe the bug
Displaying the directory stops at a random position and shows strange characters:

Even disabling the JiffyDos support using POKE $d698, $6A does not help.

Same Core and ROM on a R3 does not show this problem. See related discussion here: https://discord.com/channels/719326990221574164/1269748016084942848/1277240336040857665

To Reproduce
Steps to reproduce the behavior:

1. Install the Core and the ROM as described here: https://wiki.eilers-online.net/IEC-Core-Test
2. Connect a SD2IEC device, switch the device numbers of the internal drives via the Freezer menu and make a DIR call.
3. The dir call stops at a random position.

Additional context
I will reevaluate this issue after the Release of Core 0.97 that includes the Hardware IEC support.

[eilers]

Tested again with Core #154 14cdc2c:
The issue is still the same:
The core works without problems until the ROM version is used that supports the new IEC hardware.
As this problem does not occurs on a R3 machine, it is still unclear whether it is a problem in combination with the core or any other side effect that is hardware related.