Like many other DMR networks, DVSPh discontinued support for reflectors some time ago.
Reflectors were originally designed to help amateur radio users familiar with D-Star transition more easily to DMR.
There are also technical limitations—such as proprietary DVSPh backend servers—that prevent routing talkgroups to reflectors.
That said, you may still be able to access DMR+ reflectors via DVSPh's IPSC2 / DMR+ servers. However, since these are no longer officially supported by the network, there is no guarantee they will work, nor is any support provided.