NHibernate creates query with incorrect parameter list

I'm getting a GenericADOException with the message:

could not execute query

related to the following query, being generated by NHibernate:

select aggregated0_.Id as col_0_0_
     , aggregated0_.Name as col_1_0_
     , aggregated0_.Event as col_2_0_
     , cast(count(distinct aggregated0_.Code) as INT) as col_3_0_ 
from Events aggregated0_ 
where 
    aggregated0_.RelatedId=@p0 
    and aggregated0_.S_Id=@p1
    and aggregated0_.HappenedAt >=@p2
group by 
    aggregated0_.Id
    , aggregated0_.Name
    , aggregated0_.Event    

Name:p1 - Value:97c58b27-460d-4fae-8185-b215e2d11882  
Name:p2 - Value:4d3b7583-4b46-46e2-8bcd-169b26fd3541  
Name:p3 - Value:7/25/2017 11:00:00 PM

As you can see, the parameter list is, incorrectly, using p1, p2 and p3. However, the query needs p0, p1 and p2.

Why is NH creating an incorrect parameter list?

Mapping:

public AggregatedEventMap()
{
    SchemaAction.None();

    Table("Events");
    ReadOnly();
    Not.LazyLoad();

    Id(e => e.E_Id).GeneratedBy.Assigned();

    Map(m => m.RelatedId);
    Map(m => m.S_Id);
    Map(m => m.P_Id);
    Map(m => m.Id);
    Map(m => m.Name);
    Map(m => m.Code);
    Map(m => m.Event);

    Map(m => m.EventTime).CustomType<UtcDateTimeType>();
    Map(m => m.HappenedAt).CustomType<UtcDateTimeType>();
}

Query is built as follows:

var query = 
    Session
        .Query<AggregatedEvent>()
        .Where(e => e.RelatedId == parameters.RelatedId);

        if (parameters.S_Id.HasValue)
        {
            query = 
                query.Where(e => e.S_Id == parameters.S_Id.Value);
        }

        if (parameters.P_Id.HasValue)
        {
            query = query.Where(e => e.P_Id == parameters.P_Id.Value);
        }

        if (parameters.Id.HasValue)
        {
            query = query.Where(e => e.Id == parameters.Id.Value);
        }

        if (parameters.FromDate.HasValue)
        {
            query = query.Where(e => e.HappenedAt >= parameters.FromDate.Value);
        }

        if (parameters.ToDate.HasValue)
        {
            query = query.Where(e => e.HappenedAt < parameters.ToDate.Value);
        }

var results =
    query
        .GroupBy(e => new { e.Id, e.Name, e.Event })
        .Select(
            g => 
                new AggregatedEventResult
                {
                    Id = g.Key.Id,
                    Name = g.Key.Name,
                    Event = g.Key.Event,
                    Count = g.Select(e => e.Code).Distinct().Count()
                })
                .ToList();

Furthermore, this doesn't happen consistently and only happens in one runtime environment. It only happens when a certain combination of parameters is used:

RelatedId, S_ID and when HappenedAt is queried for events on, or after a given date.