Thanks for reporting this - we have fixed the issue which was isolated to setting custom amounts on subscriptions - a new version 1.4.1 should be live in the next 24 hours with the fix
nostr:nprofile1qqswfa547pdmqkerzf2uen3agudc67wxffjmenqpge3dylc006fppyspp4mhxue69uhkummn9ekx7mqpzemhxue69uhhyetvv9ujumn0wd68ytnzv9hxgqgkwaehxw309aex2mrp0yh8qunfd4skctnwv46qa3xytq fountain subs are buggy.
You say sub from $5 (5.530 sats) which is then converted to $55.30 incorrectly and that amount is calculated in sats (61.162) .
This is a serious bug fix it soon.
Discussion
Fix is now live in version 1.4.1