IMO investors are looking at Capstone as a one trick pony that has done a great job with puck lights but has shown minimal growth in other product offerings. For example, where are the CPC bulbs? especially during this hurricane season. I know that may not be true but the company has not put out any specific PR to counter such assumptions. Therefore in the absence of direct evidence of diverse product sales success, the stock is languishing. Further, investors see that they basically sell to Sanm's Club and Costco and the concentration of those 2 sales channels is very risky. Just image if heaven forbid one of those accounts are lost.
Also, the sales price for most LED products are decreasing which affects margins. There is always some Chinese or foreign competitor that is willing to undercut the price to break into market share. With all of those concerns the company needs to be ahead of the curve with innovative product offerings.
Other than that I have no idea why the stock has gone nowhere.