I just set up a one-machine cluster on a Fedora workstation, using the default package (8.8.10), and this is my first time setting up a condor cluster using roles. I followed the "quick start" guide in the administration part of the manual, setting CentralManager, Exec, and
$ condor_q -better-analyze 2.0
-- Schedd: clh-8842.lab.core : <
172.16.8.48:9618?...
The Requirements _expression_ for job 2.000 is
  (TARGET.Arch == "X86_64") && (TARGET.OpSys == "LINUX") && (TARGET.Disk >= RequestDisk) && (TARGET.Memory >= RequestMemory) &&
  (TARGET.HasFileTransfer)
Job 2.000 defines the following attributes:
  DiskUsage = 1
  ImageSize = 1
  RequestDisk = DiskUsage
  RequestMemory = ifthenelse(MemoryUsage =!= undefined,MemoryUsage,(ImageSize + 1023) / 1024)
The Requirements _expression_ for job 2.000 reduces to these conditions:
    ÂSlots
Step  ÂMatched ÂCondition
----- Â-------- Â---------
[0] Â Â Â Â Â36 ÂTARGET.Arch == "X86_64"
[1] Â Â Â Â Â36 ÂTARGET.OpSys == "LINUX"
[3] Â Â Â Â Â36 ÂTARGET.Disk >= RequestDisk
[5] Â Â Â Â Â36 ÂTARGET.Memory >= RequestMemory
[7] Â Â Â Â Â36 ÂTARGET.HasFileTransfer
No successful match recorded.
Last failed match: Thu Sep 10 18:03:28 2020
Reason for last match failure: no match found
002.000: ÂRun analysis summary ignoring user priority. Of 36 machines,
   0 are rejected by your job's requirements
  Â36 reject your job because of their own requirements
   0 match and are already running your jobs
   0 match but are serving other users
   0 are able to run your job
WARNING: ÂBe advised:
 ÂJob did not match any machines's constraints
 ÂTo see why, pick a machine that you think should match and add
  Â-reverse -machine <name>
 Âto your query.
For what it's worth, adding "-reverse -machine clh-8842.core.lab" to the query didn't return anything useful.
I'm guessing the problem might be the "undefined" in the RequestMemory attribute, but I'm not sure, and I'm not sure why it's undefined.