Lost Mine of Phandelver Bug Report - goblin ambush map missing

I have just purchased the lost mine of phandelver module, and the goblin ambush map is blank and named ' random battle map' and only loads a blank map, while all the other maps appear to be fine. I am using google chrome 66.0.3359.181and macOS high sierra v10.13.3. Javascript is enabled, I am not using anti virus software. my enabled browser extensions include adblock, google drive, honey, last pass, momentum, ookla, zotero and ebay, none of which have affected anything before, Please see trhe attached image for the error   Thank you for your help, Jordan

2. Goblin Ambush Roll20 Note: There is no Battle Map provided for the campaign's first encounter. If you would like to utilize a grid for the Goblin Ambush, we've provided the "Random Battle Map" Page for quick one-off fights that may occur throughout your adventure. It is stated in the "Overview of Act 1" handout about the Goblin Ambush (see text above).

thank you very much