title="yes" behaving oddly?

If I set the shortcode to the following

[zotpress year=”2015,2014″ style=”chicago-author-date” sortby=”author” title=”yes”]

I get a list that’s ordered oddly by author, within the yearly titles…

2015

Yu, Y. M., Y. H. Chan, P. C. Calder, A. Hardjojo, S. E. Soh, A. L. Lim, H. L. Fisk, et al. 2015. “Maternal PUFA Status and Offspring Allergic Diseases up to the Age of 18 Months.” Br J Nutr, March, 1–9. doi:10.1017/S000711451500001X.

Roberts, H. C., H. E. Syddall, J. W. Butchart, E. L. Stack, C. Cooper, and A. A. Sayer. 2015. “The Association of Grip Strength With Severity and Duration of Parkinson’s: A Cross-Sectional Study.” Neurorehabil Neural Repair, February. doi:10.1177/1545968315570324.

Moon, R. J., N. C. Harvey, J. H. Davies, and C. Cooper. 2015. “Vitamin D and Bone Development.” Osteoporos Int 26 (April): 1449–51. doi:10.1007/s00198-014-2976-y.

Lahti, M., J. G. Eriksson, K. Heinonen, E. Kajantie, J. Lahti, K. Wahlbeck, S. Tuovinen, et al. 2015. “Late Preterm Birth, Post-Term Birth, and Abnormal Fetal Growth as Risk Factors for Severe Mental Disorders from Early to Late Adulthood.” Psychological Medicine 45 (April): 985–99. doi:10.1017/S0033291714001998.

Keevil, V. L., K. Wijndaele, R. Luben, A. A. Sayer, N. J. Wareham, and K. T. Khaw. 2015. “Television Viewing, Walking Speed, and Grip Strength in a Prospective Cohort Study.” Med Sci Sports Exerc 47 (April): 735–42. doi:10.1249/MSS.0000000000000453.

Davey, T., S. A. Lanham-New, A. M. Shaw, R. Cobley, A. J. Allsopp, M. O. Hajjawi, T. R. Arnett, P. Taylor, C. Cooper, and J. L. Fallowfield. 2015. “Fundamental Differences in Axial and Appendicular Bone Density in Stress Fractured and Uninjured Royal Marine Recruits – A Matched Case-Control Study.” Bone 73 (April): 120–26. doi:10.1016/j.bone.2014.12.018.

Culliford, D., J. Maskell, A. Judge, C. Cooper, D. Prieto-Alhambra, N. K. Arden, and C. OASt Study Group. 2015. “Future Projections of Total Hip and Knee Arthroplasty in the UK: Results from the UK Clinical Practice Research Datalink.” Osteoarthritis Cartilage 23 (April): 594–600. doi:10.1016/j.joca.2014.12.022.

But I also get additional yearly titles..

so

2015
…
…
…
2014
…
…
…
…
…
2015
…
…
…

Not sure why I’m getting additional 2015 titling at the the bottom of the list. The references under that last 2015 title, seem to be duplicates of ones in the first 2015 list.

I’ve tried it with other styles, nature, BMJ but they output similar oddities.

https://ww.wp.xz.cn/plugins/zotpress/