When R2 & R5 are route reflectors (RRs), routes from R4 & R8 are advertised to R5 and R5 advertises to R2. But R2 would drop them as R2 is also a RR. Therefore some routes are missing on R1 to advertise to eBGP peers.
Good reference:
https://www.ciscolive.com/c/dam/r/ciscolive/emea/docs/2015/pdf/TECRST-2310.pdf Route reflectors (RR) must be fully iBGP meshed so we cannot configure RR on both R1 and R5.
We should choose routers at the center of the topology RRs, in this case R4 & R5.

If you use tags to filter the templates, you must apply the same tags to the device to which you want to apply the templates. Otherwise, you get the following error during provisioning: -Cannot select the device. Not compatible with template.