I am experiencing the same symptoms with my M5Paper and Windows 10.
If I run and download an m5 file that contains about 1400 blocks it does not work, but if I delete the blocks to make it about 400 blocks it works.

M5 paper
This problem occurs with all combinations of UIFlow-Desktop-IDE (Win) v1.0.16, v1.0.17 and firmware versions v1.7.7, v1.7.8.

A sample m5 file (about 1250 blocks, the event also occurs with this file)
https://github.com/collelog/m5paper-dashboard/blob/master/src/weather-jp.m5f

These m5 files used to be able to be run and downloaded in conjunction with UIFlow(Web), but UIFlow(Web) is no longer available, as shown in the following topic.
https://forum.m5stack.com/topic/3361/uiflow-cannot-currently-connect-to-any-m5stack-devices