Hi colec518,
In official support, we only allow the CEA mode. Such mode like 1440x2560 may be filtered out by the hdmi driver.
A workaround here is to comment out below line in “tegra_hdmi_fb_mode_filter” in hdmi2.0.c and rebuild the kernel.
320 if (mode->xres > 4096 || mode->yres > 2160)
321 return false;