Part of Automation disappeared after saving

Hello, I am using ardour which installed from pacman of Arch Linux. Its version is 8.2-1

I draw automation of Midi CC 64 in order to control the pedal of the piano. After I saved my files, then reopened it, the automation just left the head part of it, and the rest remained blank, with no points.
I found a discussion which about three years ago and similar to this situation, it said that the points may lost if they stay too close. Though I think the situation of mine may not cause by that, drawing points which really close to each other may not to avoid.

Anyway, I wonder if it is a bug or I did something wrong which caused that. And I wonder if there is a much easier way to control pedal. Thanks a lot for your help!

The down one is a sample before I save the file,
And it could be like the up one after I save it and reopen.