Can't run more than 12 concurrent tasks in gitea action

Hey, everybody.
I don’t know if this has been a topic before, but there is a problem with the number of concurrent tasks in gitea action.
The problem is that when running more than 12 concurrent ci processes, only 12 tasks can work in parallel without problems, all others automatically terminate without success, and I have to wait until the end of those that work, to complete all tasks, and this is a problem because I do it manually, or run build queues of no more than 12 concurrent tasks.
In the settings of the act runner config file I have set the following values
“# Execute how many tasks concurrently at the same time.
capacity: 64”
I use gitea on a server with the characteristics below:
CPU: Intel® Xeon® E5-2680v3 24C/48T
RAM: 128GB
SSD: 1Tb Raid1
OS: Ubuntu 20.04
Gitea is running on docker, version 1.22 and act_runner nightly
Can anyone who has faced this problem help to solve please.