On Media Composer 2018.12.1 around 5 weeks ago downloaded the Nablet XAVC-S plugin as have footage ftom Sony fs7, Sony a7sii and Gopro. All footage Ama'ed into Media Composer to complete an online and then transcode to Avid DNXHR.

1. With the Nablet trial it shows the watermark on the Sony a7sii.

2. Bought the Nablet XAVC-S plugin. Entered the code, rebooted the system.

3. Avid Media Composer re-opening the AMA online sequence, all the footage with .mp4 filename such as the Sony as7ii and Gopro are all showing as offline.

4. Error comes up saying Exception: Failed to get sample position, with the sequence with the AMA from those cameras.

5. Source AMA files in the bin with the mp4 when they are clickd they don't load into the source and show the same error  Failed to get sample position. The thumbnail in the bin now shows ink/green spilit screen for the mp4 files?

6. Tried to re-link ama to the as7ii and Gopro and got the same exception error Failed to get sample position.

Has Nablet corruptd the way Avid sees the generic mp4 such as the Gopro?

Try deleting your Avid AMA cache files. Solved problem for me.

Have a go at completely uninstalling the XAVC-S plugin by Nablet and try AMA linking to the MP4 files using the quick Alt+Drag-drop function. I've found that MC 2018.12.1 will successfully AMA to XAVC-S files and also displays the correct TCs via the Generic plugin that comes pre-intalled.

It could be that your Nablet plugin is interfering with Avid's generic plugin. Or you could force it to use the Generic Plugin via the 'Link With' option in Source Browser should you prefer to try without uninstalling Nablet.