I have my Arducam 64mp working for the most part. I set it up using the short ribbon cable. It worked but intermittently, maybe 1 in 4 commands will capture an image. Then I installed the Cat5 extension cable system, same issue. I did try the installation from the extension cable notes with the imx519 low speed driver, but nothing works then. My dmesg looks like this.
[ 9.790647] arducam_64mp 10-001a: Device found Arducam 64MP.
[ 9.825357] arducam_64mp 10-001a: Consider updating driver arducam_64mp to match on endpoints
[ 53.085344] arducam_64mp 10-001a: Failed to write reg 0xb0b9. error = -5
[ 53.085355] arducam_64mp 10-001a: arducam_64mp_start_streaming failed to set common settings
[ 62.095103] arducam_64mp 10-001a: Failed to write reg 0x98d9. error = -5
[ 62.095113] arducam_64mp 10-001a: arducam_64mp_start_streaming failed to set mode
[ 68.174967] arducam_64mp 10-001a: Failed to write reg 0x33f2. error = -5
[ 68.174978] arducam_64mp 10-001a: arducam_64mp_start_streaming failed to set common settings
[ 86.134675] arducam_64mp 10-001a: Failed to write reg 0x883c. error = -5
[ 86.134693] arducam_64mp 10-001a: arducam_64mp_start_streaming failed to set common settings
[ 218.321348] arducam_64mp 10-001a: Failed to write reg 0x5c51. error = -5
[ 218.321364] arducam_64mp 10-001a: arducam_64mp_start_streaming failed to set common settings
[ 280.200731] arducam_64mp 10-001a: Failed to write reg 0x923a. error = -5
[ 280.200751] arducam_64mp 10-001a: arducam_64mp_start_streaming failed to set common settings
[ 286.480459] arducam_64mp 10-001a: Failed to write reg 0x5bfb. error = -5
[ 286.480470] arducam_64mp 10-001a: arducam_64mp_start_streaming failed to set common settings
[ 288.570620] arducam_64mp 10-001a: Failed to write reg 0x5c5d. error = -5
[ 288.570630] arducam_64mp 10-001a: arducam_64mp_start_streaming failed to set common settings
[ 296.510470] arducam_64mp 10-001a: Failed to write reg 0x0349. error = -5
[ 296.510489] arducam_64mp 10-001a: arducam_64mp_start_streaming failed to set mode