QT Support stated today that QV Engines are assigned based on the start time of the task. So, if Task A has just finished the reload phase, releases its engine, enters into the distribution phase and is seeking a QlikView engine – one would be assigned based on the start time of the task. This should mean that this original task should get priority over any task that is chronologically ‘later’ (which is a good thing).
As you don't need to distribute the report and want to do the reload only , than in this case you can create a External task , which pass only reload instruction to the QMC.
"qv.exe file path\qv.exe" \r "application path\application_name.qvw"
Pass the above command while creating the external task.
NOTE:- In this you won't get the task log in QMC.
For future readers: I worked with Qlik support to switch to "Distribute to Folder". I found that when you configure a task to "Distribute to QlikView Server" it does occupy two engines - one to refresh and a second one to distribute. If you utilize "Distribute to Folder" you only use a single engine to refresh. This solved my original issue and did seem to work well for us.
One down side, however, is impact on future system upgrades and migrations. There are situations (upgrades/migrations) that would require you to manually adjust each "Distribute to Folder" Path property. We used this method for a few years and this problem of hard-coding the distribution to folder path came up twice in the context of upgrades/migrations (we had several hundred tasks and would have needed to modify about half of them manually). We have since switched back to "Distribute to QlikView Server" so we can be in a better position for future upgrades (our original challenge with engines has been resolved with environment upgrades).