Same Problem here. I created a cronjob whith "docker restart swag" which restarts my swag every hour to avoid problems, but this sucks.
Log of swag shows no problems.
Using Let's Encrypt as the cert provider
SUBDOMAINS entered, processing
SUBDOMAINS entered, processing
Sub-domains processed are: xxx
E-mail address entered: xxx
http validation is selected
Certificate exists; parameters unchanged; starting nginx
The cert does not expire within the next day. Letting the cron script handle the renewal attempts overnight (2:08am).
[custom-init] No custom files found, skipping...
[ls.io-init] done.
Server ready