I just tried yours and it gives the same warning while doing the placement.
Analog Code Generation...
Warning: placer did not place the following components:
The reason for the warning is because placer really did not place the SARMUX component
Note that unlike PSoC 4, where PSoC Creator's fitter/placer does a lot of placement stuff for you, in PSoC 6 there is not much placement done by PSoC Creator. Especially for the SAR ADC, which can be handled completely in firmware using the sar PDL. Basically the SARMUX is configured and enabled as part of the PDL init and not PSoC Creator init. Hence PSoC Creator does not (or rather will not) handle the placement of the SARMUX.
This is not an issue and your project should work and make full use of the SARMUX, if that is what you are worried about
Meenakshi Sundaram R
Thank you Meenakshi. I will ignore the warning from now on.