I am facing the same problem as JENKINS-42584, though I am using a new version of Priority Sorter.

Priority sorter global configuration:

• Strategy: Absolute
• Number of priorities: 5
• Default priority: 3

Job priorities: A single job group:

• Jobs to include: All
• Priority: Default
• Use additional rules when assigning a priority to a Job: checked
  The additional strategies from top to bottom are "Job Triggered by a Upstream Build" and "Use Priority from Build Parameter Build Parameter Name". The parameter is called BuildPriority.

Jobs:
I have a pipeline called "priority test trigger" which has the parameter BuildPriority and will call another pipeline "priority test" by groovy script

build(job:"first folder/prioity test",wait:true)

When I run "priority test trigger" with BuildPriority 1, here is my logs with Logger: PrioritySorter.Queue.Items and FINER level.

May 11, 2021 5:10:07 PM FINER PrioritySorter.Queue.Items
New Item: Id: 1224, JobName: prioity test trigger, jobGroupId: 0, reason: Use Priority from Build Parameter, priority: 1, weight: 1.0, status: WAITING
Evaluating JobGroup [0] ...
Evaluating strategies ...
Evaluating strategy [Job Triggered by a Upstream Build] ...
Evaluating strategy [Use Priority from Build Parameter] ...
Strategy is applicable

May 11, 2021 5:10:07 PM FINE PrioritySorter.Queue.Items
Starting: Id: 1224, JobName: prioity test trigger, jobGroupId: 0, reason: Use Priority from Build Parameter, priority: 1, weight: 1.0, status: WAITING
May 11, 2021 5:10:07 PM FINER PrioritySorter.Queue.Items
New Item: Id: 1225, JobName: prioity test, jobGroupId: 0, reason: Job Triggered by a Upstream Build, priority: 3, weight: 3.0, status: WAITING
Evaluating JobGroup [0] ...
Evaluating strategies ...
Evaluating strategy [Job Triggered by a Upstream Build] ...
Strategy is applicable

May 11, 2021 5:10:16 PM FINE PrioritySorter.Queue.Items
Starting: Id: 1225, JobName: prioity test, jobGroupId: 0, reason: Job Triggered by a Upstream Build, priority: 3, weight: 3.0, status: WAITING
May 11, 2021 5:10:17 PM FINER PrioritySorter.Queue.Items
New Item: Id: 1226, JobName: part of first folder » prioity test #12, jobGroupId: -1, reason: <none>, priority: 3, weight: 3.0, status: WAITING

May 11, 2021 5:10:17 PM FINE PrioritySorter.Queue.Items
Buildable: Id: 1226, JobName: part of first folder » prioity test #12, jobGroupId: -1, reason: <none>, priority: 3, weight: 3.0, status: BUILDABLE
May 11, 2021 5:10:17 PM FINE PrioritySorter.Queue.Items
Starting: Id: 1226, JobName: part of first folder » prioity test #12, jobGroupId: -1, reason: <none>, priority: 3, weight: 3.0, status: BUILDABLE