Hello!
I can immediately spot several problems here.
1. It is not recommended to leave the trigger that closes a block outside of that block. It should be preferred to keep it inside, as the first trigger in that block.
2. The trigger that closes the block must not be set to "repeat no more often than X sec.". Instead it is the block itself that should be repeated. The trigger that closes it works once per market, the block gets closed, all the triggers inside get reset, including the closing trigger.
3. If you set the block to be checked every 600 sec (=10 min) and set the condition to check the time between 21:10 and 21:20, there is a great chance the condition will never be met. Why? Because BetFair may delay the refresh, your Internet connection may glitch etc. As a result, the market will be refreshed, say, at 21:09 and the next time it will be refreshed at 21:21. Always leave some space for possible delays.
Please see the corrected triggers attached.