An unrecognised Maurice Denis?

Van Ham, Germany, sells on 18 November a "French Master, 19th / 20th century" "Bathers at the lake", estimated at 6,000 to 8,000 Euro. It has a partial signature "Mau D."

Rather a high estimate for an anonymous work.

The signature is one used by Maurice Denis (1870-1943), an influential French painter of the late 19th century. His later work is less interesting, though still fairly good. The signature reads "Mav. D" with a faded "en..." after it (the last character seems to be a 1, so perhaps 91?).

Turns out that the work, in an uncleaned state, was sold as by Maurice Denis somewhere in the past (I haven't found the actual auction nor the year or the result). It was then dated to 1890-1894, which would put it right in the most interesting period of Denis. Has the attribution been lost since then? Doesn't the auction house believe it to be by Denis? Or are they trying to lure the bidders by "not knowing" who the artist is?

The work for sale is influenced by pointillism and looks almost like a design for a tapestry. If it is an actual work from the early 20th century but with an apocryphal signature, it should be worth the estimate. If it is real Maurice Denis from the late 19th century, and this can in some way be authenticated, then it should be worth around 200,000 Euro instead!

UPDATE: sold for 6,000 Euro, either no one recognised the signature or no one believed it to be real!