Spotted this 'odd' behavior with the UNO Synth and Editor, though I think the issue is with the Synth itself.
When attempting to save a preset with a (very) complicated sequence - ie lots of notes/parameters changing, I am finding that the '.unosyp' file seems to missing the sequencer information and is noticeable smaller in file size. When re-uploaded to the synth it is therefore missing it's sequence pattern.
The same preset can be copied (stored to new location) within the UNO Synth and maintains it's sequencer pattern.
If a few items are deleted/cleared from the pattern, then it successfully downloads/uploads. The threshold of 'bad' may be the number of items (around 60 notes/parameters in total *) in the pattern, or maybe the overall length of the resultant config file.
* If you are thinking 'What is he doing!!!", remember that you can sequence midi CC and it seems to store/replay 21 different CC types.