Just got an Indivision ECS v3 and while the video output seems to work great, I'm having issues with the mouse jumping horizontally randomly. I've tested it on two Amiga 500, both with revision 5 PCB.
One of them has a Vampire 500 V2+. On this one, the cursor jumps to the left randomly. It does not happen when using low res modes, or in high res mode with 2 colors, only in high res mode with 4 colors or more. With the original Denise chip I do not see this issue.
The other one has a 68000 CPU and a home made RAM/IDE board, stacked under the CPU. I see a similar jumpiness on this one, but it jumps to the right. I have not tried yet without the RAM/IDE board.
The only thing I see on the wiki that could be even vaguely related is this point in the changelog for the firmware: "Improve compatibility with certain Rev6 boards that showed 'jumpy mouse' behavior. One of the sample points for the mouse has been moved to improve stability." I'm open to taking some oscilloscope measurements if that could help. I assume there is no way of changing the timing of the sampling without making a new firmware.
Any help or ideas appreciated!