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.
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)
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.