So am on my 5th one since Nov 29 - 2 of which never arrived thanks to DPD. All 3 that came have had the same issue - despite multiple mappings they just give up during a clean and stop without any resumption being offered or returning to the dock. All have been charged and I  have  tried with with just a single room mapped to make it easier (and different rooms). Have followed instructions to the letter, ensured good lighting and rooms prepared. The impression is of a well engineered powerful machine with terrible software / firmware / navigation that is closer to an alpha rather than a beta evolution with buyers being asked to do the R&D. Is am a Dyson advocate over many years but this is shocking for a £1200 machine. 
I chose Dyson over the competitors because of past excellence and after sales service but am thankful I can return this within 90 days (although have so far lost 21 of them due to none appearance of replacements thanks to DPD.

Anyone any insight that may sort this or is it as bad as I imagine and I should have bought the Roborock. Thanks Nick