rasplex switches source when I turn on my TV

Ive tried disabling CEC and adding hdmi_ignore_cec_init=1 to the config file but still nothing. what am I missing here?

Don’t really understand the question, Rasplex is a ‘source’ for your TV.

Is your scenario as follows:

Watch TV using a source other than Rasplex then switch off TV.
Switch on TV, source is Rasplex.

If so, then it is your TV that is automatically switching sources, look at the TV settings.

Regards