The manual says “Hotspot default profile for Hotspot users” so that value may only be valid for the Hotspot function. I’m not 100% on that but if you can get it working fine for hotspot but not PPPoE then it sounds likely. I know from my own testing that there are a lot of supported radius attributes that are only valid for certain services.
If your goal is to bandwidth limit the user using queues then I’m only aware of two solutions. (I’m currently using the first (simple) method although we’ve been testing the second method to give us better control over contention)
Use the Mikrotik-Rate-Limit radius attribute (Appears to be same format as you’re already using)
A new queue is created dynamically when the users connects which is applied to their PPPoE interface. This is really easy and just works.
The downside with this is that if 5 users all log in with say 10M limits, they all get their own 10M queue, allowing these users to use up to 50M of bandwidth combined, whereas we’d prefer to have a smaller cap on the group to provide contention.
Use the Mikrotik-Address-List attribute to add the user’s PPPoE address to an address list
Using this method takes a bit more work but provides more control. You can configure, via radius, multiple users to go into the same address list, then use firewall mangle rules to tag all their traffic. After that you can use PCQ queues to apply an overall limit for all the tagged traffic, but also have individual limits for each user (using src/dst address to distinguish them).