PBRS Invalid character in subscription file share authentication user name

We have a RDL report in PBRS with a subscription that should create PDF files and deliver them to a Windows file share. It had a problem with authentication so I temporarily changed the user name to something like 'Do not use admin account here!' and a blank password. I could save that change, but after having done that I'm unable to open the subscription section for that report. I get an error saying:

'An error has occured. Somehing went wrong. Please try again lagter'

I suspect that the problem is caused by the ! being an invalid character as the user name, but unfortunately it managed to save the invalid setting.

The PBRS log file says the following:

2019-04-11 12:29:03.1730|ERROR|32|OData exception occurred: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.FormatException: String was not recognized as a valid DateTime.
   at System.DateTimeParse.Parse(String s, DateTimeFormatInfo dtfi, DateTimeStyles styles)
   at Microsoft.ReportingServices.Portal.Services.ODataExtensions.ParameterValueExtensions.FormatAsISO8601Date(String date, String culture)
   at Microsoft.ReportingServices.Portal.Services.ODataExtensions.ParameterValueExtensions.ToWebApiReportParameterValue(ParameterValue parameterValue, ReportParameterType reportParameterType, String culture)
   at Microsoft.ReportingServices.Portal.Services.ODataExtensions.SubscriptionExtensions.ToReportPameterList(SubscriptionImpl librarySubscription, Dictionary`2 parameterTypes, String culture)
   at Microsoft.ReportingServices.Portal.Services.ODataExtensions.SubscriptionExtensions.ToWebApiModel(SubscriptionImpl librarySubscription, Dictionary`2 parameterTypes, SubscriptionProperties properties)
   at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Microsoft.ReportingServices.Portal.Repositories.CatalogItemRepository.GetSubscriptions(IPrincipal userPrincipal, String itemPath)
   at Model.Report.get_Subscriptions()
   at lambda_method(Closure , ReportRepository )
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
   at System.Delegate.DynamicInvokeImpl(Object[] args)
   at System.Web.OData.Query.Expressions.SelectExpandBinder.Bind(Object entity)
   at System.Web.OData.Query.SelectExpandQueryOption.ApplyTo(Object entity, ODataQuerySettings settings, IAssembliesResolver assembliesResolver)
   at System.Web.OData.Query.ODataQueryOptions.ApplySelectExpand[T](T entity, ODataQuerySettings querySettings)
   at System.Web.OData.Query.ODataQueryOptions.ApplyTo(Object entity, ODataQuerySettings querySettings)
   at System.Web.OData.EnableQueryAttribute.ExecuteQuery(Object response, HttpRequestMessage request, HttpActionDescriptor actionDescriptor)
   at System.Web.OData.EnableQueryAttribute.OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
   at System.Web.Http.Filters.ActionFilterAttribute.OnActionExecutedAsync(HttpActionExecutedContext actionExecutedContext, CancellationToken cancellationToken)
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Filters.ActionFilterAttribute.<CallOnActionExecutedAsync>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Filters.ActionFilterAttribute.<ExecuteActionFilterAsyncCore>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Controllers.ExceptionFilterResult.<ExecuteAsync>d__0.MoveNext().| RequestID = s_2569de68-0f08-44fd-a591-804161aa864b
2019-04-11 12:29:03.1730|INFO|33|Sending response. Response code CARNNET\magnec 500, Elapsed time 0:00:00.0453356| RequestID = s_2569de68-0f08-44fd-a591-804161aa864b

Currently it seems like the only option I have to fix the problem is to delete the whole report and deploy it again.

PBRS Version 1.4.6969.7395 (January 2019)