The first question as usual is Have you checked the logs? Let's start from the program logs as they are easier to find. They may contain an error message which will be the reason why a bet is not placed.
If nothing suspicious there, then on to the steps below.
1. Make sure markets are not deleted automatically once finished or settled.
2. The previous Over/Under markets (in your case, the Over/Under 1.5) must have a WINNER label across the winning selection for the betting to resume in the next markets. If it's not there, it means the market is not settled yet.
3. Check if the match score is actually being updated for that event: when there is a huge number of markets going at the same time, the score may be delayed.
4. If none of the above helps, do check the logs for the trigger "Total Score = 2" - it is the one responsible for laying in Over/Under 2.5. See which condition does not get satisfied.