On webdashboard I noticed missing strings for Thimble, but Pontoon locale and project dashboard do not know about them until you change a string there. See https://pontoon.mozilla.org/projects/thimble/ or https://pontoon.mozilla.org/bn-BD/, where Thimble is shown 100% complete with 255 strings in total, while on https://pontoon.mozilla.org/bn-BD/thimble/ there are 25 strings missing and the sum is 280 strings. After I started adding suggestions for Thimble, it is already shown correctly for Czech (cs), but that won't help those localizers, who check their team dashboard only. Not sure if other projects are affected too.
Thanks for reporting! It is indeed a bug in how we update stats after sync. If only the source (en-US) file changes, we not only skip syncing locale files, but also updating stats. In practice it only affects 6 projects using .properties files.
Commit pushed to master at https://github.com/mozilla/pontoon https://github.com/mozilla/pontoon/commit/4289e65815286a427850b12fa8140a2323f56021 Fix bug 1292890: Sync stats if only resources changed in monolingual files (#448)