One task QRunnable does not call a destructor

[AlekseyB]

using uint64 = unsigned int64_t;
using cuint64 = const uint64;
using string = std::string;
using cstring = const string;

class SyncTask: public QRunnable
    {
        cstring Information;

        const string& GetMirrorOfDataOnHDD();

    protected:
        uint QuantityError;
        const VariativeData& Settings;

        virtual void BasicProcedureOfTask(cstring& MirrorOfDataOnHDD) = 0;
        virtual SyncTask* CreateNewTask() = 0;

    public:
        cuint64 Key;

        SyncTask(const VariativeData& Settings_,
                 cstring& Information_,
                 uint QuantityError_);

        virtual ~SyncTask();

        void run();
    };

class CountFile final: public SyncTask
    {
        cstring SubPathToFile;
        std::unordered_map<string, uint16>* const Tickers;

        void GetDataFromTextFile(cstring& FullPathReadFile, Array<allData>& ArrayForTask);

        void WriteFileForTicker(cstring& MirrorOfData, const MyLib::Array<allData>& ArrayOfFile, cstring& CurrentMonth, cuint16 IndexOfTicker);

        void WriteArrayToBinFiles(cstring& MirrorOfData, const Array<allData>& ArrayForTask);

        void BasicProcedureOfTask(cstring& MirrorOfData) override;

        SyncTask* CreateNewTask() override;

    public:
        CountFile(const VariativeData& Settings_,
                  cstring& SubPathToFile_,
                  void* const Tickers_ = nullptr,
                  uint QuantityError_ = 0)
            :
              SubPathToFile(SubPathToFile_),
              Tickers((std::unordered_map<string, uint16>*) Tickers_),
              SyncTask(Settings_, SubPathToFile_, QuantityError_)
        {}
    };

cuint64 Key - a unique value obtained with the help of the std::atomic<uint64>, with which I analyze the call of the destructor for tasks. In multithreaded mode, all tasks are performed, but for one is the destructor not called.

I think this is mistake of the Qt- library.