Dotnet core 3.1 not binding query parameter - asp.net

Question

When calling an HTTP get method, the query parameters are not correctly filled in.
Let me explain with the code.
[HttpGet]
public async Task<IActionResult> GetTasks(Guid propertyId, [FromQuery] TaskFilterParams filterParams, [FromQuery] SortingParams sortingParams, [FromQuery] PagingParams pagingParams)
{
// Do some stuff, not important
}
So we call this endpoint with the following url: someurl.com/api/v1/properties/[some-guid]/tasks?&roomClass=Single&category=Cleaning
As you can see, we only have provided three values, a GUID, a type of room and the category of the task. The sorting and paging parameters are empty.
The problem is that the 'category' parameter is not filled in. It is always null, while the other parameters are filled in correctly. No matter what we try (url encoding, re-arranging the order of the parameters, ...).
The real catch is however, if we restart the service, it sometimes works for a while. But every so often it fails and we need to restart evertything again.
Has anyone encountered the same issue? Or, even better, a solution?
PS: The code is running in a docker container in AKS (FROM mcr.microsoft.com/dotnet/core/aspnet:3.1).
[DBG] Get tasks parameters: PropertyId: [some-guid], TaskFilterParams:{"Category": null, "RoomClass": {"Value": "Single", "Operator": "Equal", "$type": "FilterParam`1"}, "$type": "TaskFilterParams"}
public class TaskFilterParams
{
public FilterParam<IssueCategory> Category { get; set; }
public FilterParam<RoomClass> RoomClass { get; set; }
public FilterParam<Guid?> Room { get; set; }
}
public abstract class FilterParam
{
public FilterOperator Operator { get; set; }
}
[TypeDescriptionProvider(typeof(FilterParamTypeDescriptionProvider))]
[JsonObject]
public class FilterParam<T> : FilterParam
{
public T Value { get; set; }
public static bool TryParse(string s, out FilterParam<T> result)
{
result = default(FilterParam<T>);
var filterOperators = Enum.GetValues(typeof(FilterOperator)).Cast<FilterOperator>();
foreach (var filterOperatorString in filterOperators.Select<FilterOperator, string>(x => x.ToFilterOperatorString()).OrderByDescending(x => x.Length))
{
if (s.StartsWith(filterOperatorString))
{
if (s.TryParse(filterOperatorString, out result))
{
return true;
}
return false;
}
}
return false;
}
}
public enum IssueCategory
{
Cleaning = 0,
Inspection = 1,
Maintenance = 2
}
public enum RoomClass
{
Single = 0,
Double = 1,
Family = 2
}
UPDATE:
We have added more logging. It seems the data is present in the query string but the model is not binding correctly.
Log.Debug("Query: {#query}", HttpContext.Request.Query);
Log.Debug(
"Get tasks parameters: PropertyId:{#propertyId}, TaskFilterParams:{#filterParams}, SortingParams:{#sortingParams}, PagingParams:{#pagingParams}",
propertyId, filterParams, sortingParams, pagingParams);
[16:51:35 DBG] Query: [{"Key": "category", "Value": ["Cleaning"], "$type": "KeyValuePair`2"}, {"Key": "roomClass", "Value": ["Single"], "$type": "KeyValuePair`2"}]
[16:51:35 DBG] Get tasks parameters: PropertyId:[some-guid], TaskFilterParams:{"Category": null, "RoomClass": {"Value": "Single", "Operator": "Equal", "$type": "FilterParam`1"}, "$type": "TaskFilterParams"}