Thank you for bringing this to our attention!
We have started to investigate reasons for both issue, and have found that the display issue in the 'Configure Debug Log Levels' windows could be caused by the latest Windows update. Did you have this update to the 1803 Windows version?
To be more detailed: this latest update includes a lot of changes in UI rendering Windows applications and these changes could influent on the control which we have used in the Debug Log Level's windows.
We are looking for a way to solve this and I will be back to you right we would find a solution.
Regarding absent log files in the panel, may I please ask you to tell me how many log files do you have in Developers Console?
A reason for this questions is that the IDE queries 100 files. (As a side note, we will consider changing of this limit).
Also, can you please tell me what exact log files are absent: for example, you cannot download new log files, or these log files were generated more than
twenty-four hours ago?
We would appreciate any additional information on this.
Looking forward to your response.