Hi again!
Now let's discus a little bit about your goal:
"when I select someone and assign them a task, the flow then automatically updates the task status to Available"
IN my opinion, this means:
1.- If item is already created with an 'Assigned to', person, flow shall update tasks status to Available. FRom your current procedure experience, can this scenario happen?
2.- If item did not have 'Assigned to' person defined yet, and this value is added, this modification shall trigger your flow logic to update tasks status to Available. FRom your current procedure experience, can this scenario happen?
3.- If item already had 'Assigned to' person defined, and item is modified, this modification shall NOT trigger your flow logic to update tasks status to Available.
4.- If an itemalready had 'Assigned to' person defined, and current person is replaced by another, this modification shall? shall not? trigger your flow logic to update tasks status to Available. FRom your current procedure experience, can this scenario happen?
So depending on the answers, I would suggest to add a yes/no new column (let's called 'Available set') whose default value is No, and is updated to yes by your trigger + a conditional trigger, so whenever this column value is yes, flow logic is not executed, or... activate version history on your Sharepoint list and use 'HTTP request to Sharepoint' to get current item value and previous version also. First approach is much more simple, Second approach is more elegant but more complicated to implement
Hope this helps