transgui json errors

[robot468]

1. Macos transgui 5.18.0 build 3fb1d33
2. transmission-daemon-4.0.5_1 freebsd

i have more than 1000 torrents in daemon. transgui shows json parsing error frequently (see screenshots).
Is there a way to fix this? Or at least log rpc answers from daemon?

Problem is not stably reproduced. It happens 10 to 20 times a day.