I'm using Collector for ArcGIS and cannot post attachments to a feature stored on ArcGIS Online. The map was configured and posted through ArcGIS Pro. I made sure to enable attachments. Upon hitting "Submit", the app says it is sending updates, posting attachments, and the tells me that the update failed. I attempted to open another map and I was able to post the attachments normally. Any thoughts as to what is generating the error?
I have discovered that this happens when I try to enter decimal data in ANY numerical field. Decimal entries are converted to their hexadecimal representation and this representation often fails during upload. Entries such as .25, .50, .75, .125, .0625, ... will be stored accurately no matter how many digits are specified in the attribute configuration. Other entries, such as .06 or .062 will be converted to the hex equivalent with about 15 digits of precision. If your attribute is configured to accept two decimal places, any decimal entries other than .25, .50, .75 and .00 will fail during upload.
ESRI - THIS IS A BUG!