marinelly160,
Thanks for letting us know. Next, have you tried restarting your device to see if that positively impacts the issue you’re experiencing as it pertains to saving time-lapsed videos to your iPhone? If not, please try that step and let us know how it goes.
Restart your iPhone - Apple Support
1) Press and hold either volume button and the side button until the power-off slider appears.

2) Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
3) To turn your device back on, press and hold the side button (on the right side of your iPhone) until you see the Apple logo.
While a restart can seem unimportant, it can actually resolve many minor issues with the device.
Please let us know the outcome after giving the above steps a try.
Thanks for using the Apple Support Communities.
Cheers!