We collected over 70 important data with 2 iPads and Collector. Then we realized that Collector on these iPads do not sync anymore. I copied the data to a PC (as .geodatabase files). Is there a way to convert these to layers with ArcGIS Pro?
Try using the Copy Runtime Geodatabase To File Geodatabase tool in desktop version 10.3 or above. I don't think the tool is available in ArcGIS Pro.
PS: This page may also help: How To: Access offline edits from Collector for ArcGIS directly from an Android or iOS device
Randy is correct - you couldn´t convert it in Arcgis Pro. I have done it several times in Arcmap and never lost any data that was collected.
One workaround that use to work is to shutdown Collector (double-click on homebutton and swipe) and restart Collector and sync. That have solved all our syncing problems on iOS the last year and we have more than 180 Ipads with collector.