Announce ULA route to Cisco switches via SLAAC

I have trouble with Cisco switches (specifically the CBS350 series if that matters) and local IPv6 routing. I run an x86 OpenWrt as router. Its ULA prefix is fd8e:3a8c:273b::/48 which is distributed as multiple /64 prefixes to downstream interfaces. The router's DHCP configurations for its management interface are as follow:

config dhcp 'management'
	option interface 'management'
	option dhcpv4 'server'
	option start '112'
	option limit '15'
	option ra 'server' # enable Router Advertisement
	option ra_slaac '1' # announce SLAAC for a prefix (that is, set the A flag in RA messages)
	list ra_flags 'none' # set neither M flag nor O flag
	option ra_dns '1' # RFC 8106
	option dhcpv6 'disabled' # disables DHCPv6 server on this interface to use SLAAC exclusively

I plugged a Windows PC into this subnet, and it can receive the ULA route fd8e:3a8c:273b::/48 just fine:

Active Routes:
If	Metric	Network Destination							Gateway
1	331		::1/128										On-link
19	356		fd8e:3a8c:273b::/48							fe80::f292:1cff:fe5b:208b
19	356		fd8e:3a8c:273b:80::/64						On-link
19	356		fd8e:3a8c:273b:80:90:e5cb:a7cb:a2ab/128		On-link
19	356		fd8e:3a8c:273b:80:ee0d:20ae:6531:b8ae/128	On-link
19	356		fe80::/64									On-link
19	356		fe80::ef0d:f73b:2b:a5f2/128					On-link
1	331		ff00::/8									On-link
19	356		ff00::/8									On-link

On the Cisco switch, I use the following commands:

cisco(config)#interface vlan 1
cisco(config-if)#ipv6 address autoconfig # 'autoconfig' means SLAAC while 'dhcp' means DHCPv6

I do not know why it could not receive (or autoconfigure) the ULA route:

cisco#show ipv6 route

Codes: > - Best
			I - ICMP Redirect, S - Static, C - Connected,
			ND - Router Advertisement
[d/m]: d - route's distance, m - route's metric

IPv6 Forwarding is disabled

IPv6 Routing Table - 1 entries

 ND> fd8e:3a8c:273b:80::/64 [0/0]
		via :: VLAN 1

I tried to set a static route to the ULA subnet and it failed:

cisco(config)#ipv6 route fd8e:3a8c:273b::/48 fd8e:3a8c:273b:1::1 # this the the router IPv6 address
IPv6 nexthop address fd8e:3a8c:273b:1::1 is not valid

I had to use the link-local address of the router management interface (fe80::f292:1cff:fe5b:208b) to get it done:

cisco(config)#ipv6 route fd8e:3a8c:273b::/48 fe80::f292:1cff:fe5b:208b%vlan1 vlan1 1
cisco(config)#exit
cisco#show ipv6 route

Codes: > - Best
			I - ICMP Redirect, S - Static, C - Connected,
			ND - Router Advertisement
[d/m]: d - route's distance, m - route's metric

IPv6 Forwarding is disabled

IPv6 Routing Table - 2 entries

	S> fd8e:3a8c:273b::/48 [1/1]
		via fe80::f292:1cff:fe5b:208b VLAN 1
	ND> fd8e:3a8c:273b:80::/64 [0/0]
		via :: VLAN 1

Can someone help me understand why the Cisco switch did not receive a ULA route to subnet fd8e:3a8c:273b::/48 (while the Windows PC did), and why setting a static route using the router address fd8e:3a8c:273b:1::1 failed?

P.S: I just found that my CCTV cameras behave the same way as the Cisco did: they can autoconfigure their IPv6 addresses using the advertised prefix and EUI-64. No route to the /48 subnet was auto-configured though, hence they could not be reached from other local subnets. I suspect they lack support for some sort of IPv6 standard.

I have not dug into the manual but maybe the behavior is the same as with Linux: if a host is configured to be a router then RA is ignored and SLAAC is not used. Because routers would normally participate in a routing domain, like ospfv3 or ibgp.

Edit:
But I see: