Joystick setting 'AMIGA to 1351 enabled' in M65 config menu partly disables the use of a second joystick

[MauriceMEGA65]

Since recently I have two new joysticks, and first opportunity to play games that support two players. I’ve found that the joystick port 1 behaves strange. After a while the joystick becomes non-responsive. After a few seconds or after a few minutes. Pressing the fire button on joystick 2(!) seems to release joystick 1 for a while again.
Swapping the two joysticks does not change anything. It seems to be port 1 releated.
Using the two joysticks in the C64 core works fine, it’s only on the MEGA65 core.

Tested in BASIC, Schluckauf and Showdown, core batch 2, ROM 920377.

See also here: https://discord.com/channels/719326990221574164/1180181054473109514/1181190203235389512

Update:
I think I found the issue: I had Joystick 1 port configured as 'Amiga to 1351 enabled'. Once I put it back to 'Normal', both joysticks behave as expected.

[MauriceMEGA65]

Solved in core 0.96 or later via this issue (since Amiga to 1351 does not need to be selected)?

#742