Upon enabling preserve-nexthop-hierarchy on the PTX10001-36MR, issues arose with traffic forwarding via SR-TE policy tunnels.  Disabling this command on the 36MR resolved the problem.

Preserve nexhthop requires egress chaining as well.  The below links explains the commands and its dependencies:

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/egress-chaining-edit-routing-options-forwarding-table.html

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/fib-next-hop-split-edit-routing-options-forwarding-table.html

Please add in below configs and check:

set routing-options resolution preserve-nexthop-hierarchy

set routing-options resolution rib bgp.l3vpn-inet6.0 inet6color-import MP_RESOLVE

set routing-options forwarding-table chain-composite-max-label-count 8

set routing-options forwarding-table egress-chaining spring-te

set routing-options forwarding-table chained-composite-next-hop transit no-ldp

set routing-options forwarding-table chained-composite-next-hop transit no-labeled-isis

set routing-options forwarding-table fib-next-hop-split labeled-isis

NOTE: Device requires reboot after enabling above configurations.